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CHAPTER 5 Sample Request for Proposals Template 5.1 Introduction This RFP presents sample language for household travel surveys that are based on the recom- mended standardized procedures and guidance in this report (see Chapter 2). Intentionally, the language is prescriptive, as it would be in an RFP. It should not be misinterpreted as advocating that this is how travel surveys must be done. Footnotes are provided that reference the relevant sections of Chapter 2. Where an agency-specific number or value is required (e.g., number of presentations to management), a blank is shown in which each agency should substitute its desired value or number. To make it easier to use the material in this chapter in preparing an actual RFP, the table and equation numbering are restarted at 1. Note that this template is intended to address only the Scope of Work section of an RFP. There are other documents that include complete RFPs, notably Travel Survey Manual published by the Transportation Model Improvement Program (TMIP, 1996b). 5.2 Request for Proposals 5.2.1 Scope of Work This section defines the minimum scope of work to be accomplished by the Survey Contractor. It is presented in this RFP in two subsections: Task Plan and Schedule. Task Plan Task 1: Project Work Program and Management Plan Within ____________ days of contract execution, the Contractor will meet with Agency staff to initiate the project, discuss the work plan and schedule, and define project management roles and responsibilities. The outcome of this meeting is a revised work program and project man- agement plan as initial deliverables. The Agency internal project management staff includes ____________, with overall project management responsibility; ____________, responsible for day-to-day project coordination; and, ____________, responsible for on-going data quality assurance. The Contractor will be expected to Designate a Project Manager who will serve as the single point of contact for all survey issues; Make ____________ presentations to Agency staff regarding survey progress and issues; Make presentations to and attend ____________ meetings of the Study Steering Committee; 68

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Sample Request for Proposals Template 69 Make a presentation of survey results to Agency management and staff; Prepare drafts of press releases regarding the survey effort for review and dissemination by Agency staff; and, Attend other meetings on an occasional basis as requested by the Agency Project Manager. Task 2: Develop Survey Sampling Plan The Contractor will prepare a survey sampling plan for review and discussion with Agency staff and the Steering Committee. The proposal should include a preliminary definition of the sampling plan and a discussion of Definition of the sampling frame for the main household travel survey; The number of households to be sampled, and the expected number of completed surveys, by cell of the main survey sampling frame; Need for augment samples (households that are recruited specifically for certain charac- teristics that are relatively rare in the local general population). These could include Households using specific transit modes (e.g., local bus, express bus, rail, ferry, or bicycle); Households using specific road facilities (e.g., certain highways, toll roads, or HOV lanes); Households using park-and-ride to a transit mode; and/or Households that represent other special population groups. Time dimensions of samples, including a discussion of 24-, 48-, or other hour period for main sample; Weekdays only (all days or only a subset); Weekend sub-sample (Saturday/Sunday only, or as 48-hour pairs, such as Friday/Saturday and Sunday/Monday pairs); and Summer sub-sample. The Contractor shall use the following guidelines in drawing a sample1: 1. To overcome unanticipated sample loss (refusals, etc.), a large random sample should be drawn. The sample size should be based on the expected non-response rate (which may be determined during the pretest). 2. When a telephone sample is used, the order in which telephone numbers are drawn must be preserved. For example, for a Random Digit Dialing (RDD) list, numbers generated later in the list must not be recruited before numbers listed earlier in the list. 3. If using RAND Corporation (1955) random numbers, additional sample may be created and drawn after the initial sample has been exhausted. If using RDD lists, this must not be done because the two random samples will not be related. 4. Refusal conversion should be conducted, with a maximum of five call attempts to convert an initial soft refusal (therefore six calls to the household, in total). Task 3: Survey Instruments and Data Collection Procedures Survey Questions Data elements that must be included in the survey are shown in Table 1.2 It is further expected that the Contractor shall use the response categories shown in Table 23 and the standard question wordings shown in Table 3.4 With respect to Table 2, at least the primary cate- gories must be used. However, discussion with the agency should occur to determine whether any secondary categories must be used. 1 Sample Replacement, Section 2.2.4 2 Minimum Question Specification, Section 2.1.1 3 Standardization of Categories, Section 2.1.2 4 Standard Question Wordings, Section 2.1.3

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70 Standardized Procedures for Personal Travel Surveys Table 1. Minimum questions.a Category Item Description Household Location Home address or home position in geographic terms Type of Building Detached, semi-detached, terraced, flat, etc. Household Size Number of household members Relationships Matrix of relationships between all members of the household Number of Vehicles Summary of number of vehicles from vehicle data Housing Tenure Own or rent status Re-contact Willingness to be contacted again for further surveys, etc. Personal Gender Year of Birth (Preferable to requesting age) Paid Jobs Number of paid positions and hours worked at each in the past week Job Classification Employee, self-employed, student, unemployed, retired, not employed, etc. Driving License Whether a current driver's license is held Non-mobility Indication of why no out-of-home activity was performed on a survey day including work-at-home days Education Level Highest level of education achieved Handicap Types of mobility handicap, both temporary and permanent Raceb Defined as currently measured in the U.S. Census Vehicle Body Type For example, car, van, RV, SUV, etc. Year of Production Ownership of Vehicle Household/person, lease, institution Use of Vehicle Main user of vehicle Activity Start Timec Activity or Purpose Location Where the activity was performed, unless traveling Means of Travel If activity is travel, what mode(s) was used (including specifying if a car passenger or driver) Mode Sequence Unless collected as fully segmented data Group Size Number of persons traveling with respondent as a group Group Membership Number of persons in the group who live in respondent's household Costs Total amount spent on tolls, fares and respondent's share Parking Amount spent to park a Minimum Question Specification, Section 2.1.1. b All surveys shall use the U.S. Census Bureau definition of Race. c Only start time needs to be ascertained in a time-use or activity survey because, by definition, the start time of an activity is the end time of the previous activity. Only the last activity should need an end time. In a trip-based survey, start and end time should be included. The Contractor shall include a question to verify reported non-mobility to be asked of all per- sons who report they did not travel (stayed in one place/did not leave home) during the entire travel period.5 It is strongly preferred that the Contractor also include questions that gently challenge per- sons who report non-mobility by asking for the reason(s) why no travel was made during that day. Survey Instruments The Contractor will provide a schedule of contacts and reminders for the data collection process, specifying the type of contact to be used in each step. Contractors shall include as a minimum Steps 1 through 6 from Table 4, although it is desired that Contractors employ all 11 steps,6 unless it can be shown that later steps are no longer cost-effective. For mailed materials, the Contractor shall use the following with regard to the format and appearance of the materials:7 For any materials to be returned via mail, the respondent must be provided with a stamped return envelope, preferably with instructions as to which materials should be mailed back (if any); 5 Incorrect Reporting of Non-Mobility, Section 2.4.6 6 Number and Type of Contacts, Section 2.2.1 7 Mailing Materials, Section 2.4.2

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Sample Request for Proposals Template 71 Table 2. Response categories.a Variable Primary Category Code Secondary Category Code Type of Dwelling Single-family house detached 1 Single-family house detached 10 (H2) Single-family house attached 2 Townhouse 21 Row house 22 Duplex 23 Triplex/fourplex 24 Apartment/mother-in-law suite 25 Apartment/condominium 3 Condominium 31 Rented apartment 32 Mobile home/trailer 4 Mobile home 41 Trailer/camper 42 Dorm/group quarters 5 Dormitory 51 Hostel 52 Nursing home 53 Military barracks 54 Hotel/motel 6 Hotel/motel 60 Other 9 Other 90 Relationship (H4) Self 1 Self 10 Spouse/partner 2 Husband/wife 21 De facto husband/de facto wife 22 Son/daughter 3 Natural son/daughter 31 Adopted son/daughter 32 Stepson/stepdaughter 33 Son-in-law/daughter-in-law 34 Father/mother 4 Natural father/mother 41 Adopted father/mother 42 Stepfather/stepmother 43 Father-in-law/mother-in-law 44 Brother/sister 5 Natural brother/sister 51 Adopted brother/sister 52 Stepbrother/stepsister 53 Brother-in-law/sister-in-law 54 Grandfather/grandmother 6 Paternal grandfather/grandmother 61 Maternal grandfather/grandmother 62 Grandchild 7 Grandson 71 Granddaughter 72 Other relative 8 Male 81 Female 82 Not related 9 Boarder 91 Housemate/ room mate 92 Other non-relative 93 Housing Tenure Own 1 Owned with mortgage 11 (H7) Owned without mortgage 12 Rent 2 Rent paid 21 Occupied without rent 22 Provided by job/military 3 Provided by job 31 Provided by military 32 Education Level No school completed 1 No school completed 10 (P10) Elementary school 2 Preschool/nursery 21 Kindergarten4th grade 22 High school 3 5th8th grade (junior high) 31 9th12th grade (no diploma) 32 High school diploma 33 College/university 4 Some college but no degree 41 Associate degree in college 42 Bachelor's degree 43 Post-graduate studies 5 Some graduate school, no degree 51 Master's degree 52 Professional school degree 53 Doctorate degree 54 Disability (P11) Difficulty standing 1 Difficulty standing 10 Difficulty climbing 2 Difficulty climbing 20 Visually impaired/blind 3 Visually impaired/blind 30 Hearing impaired/deaf 4 Hearing impaired/deaf 40 Require wheelchair 5 Require wheelchair 50 Require cane/walker 6 Require cane/walker 60 Other (specify) 9 Other (specify) 90 (continued on next page)

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72 Standardized Procedures for Personal Travel Surveys Table 2. (Continued). Variable Primary Category Code Secondary Category Code Race (P12) White (alone) 1 White (alone) 10 Black/African American (alone) 2 Black/African American (alone) 20 American Indian/Alaskan Native 3 American Indian 31 (alone) Alaskan Native 32 Asian (alone) 4 Asian Indian 41 Chinese 42 Filipino 43 Japanese 44 Korean 45 Vietnamese 46 Other Asian 47 Native Hawaiian or Pacific Islander 5 Native Hawaiian 51 (alone) Guamanian or Chamorro 52 Samoan 53 Other Pacific Islander 54 Some other race (alone) 6 Some other race (alone) 60 Two or more races 7 Two or more races 70 Vehicle Body Type Auto 1 Auto 10 (V1) Van 2 Van 20 Recreational vehicle (RV) 3 Recreational vehicle (RV) 30 Utility vehicle 4 Utility vehicle 40 Pick-up truck 5 Pick-up truck 50 Other truck 6 Other truck 60 Motorcycle 7 Motorcycle 70 Other (specify) 9 Other (specify) 90 Vehicle Ownership Household member owned or leased 1 Household member owned or leased 10 (V5) Employer owned or leased 2 Employer owned or leased 20 Other (specify) 3 Other (specify) 30 Trip Purpose (A2) Home 1 Home domestic activity 10 Home paid work 11 Work and work-related 2 Main job 21 Other job 22 Volunteer work and community 23 services Looking for work 24 Education/childcare 3 Attendance at childcare 31 Attendance at school 32 Attendance at college 33 Eating out 4 Restaurant/caf 41 Fast food 42 At friends' home 43 Personal business/medical 5 Availing of/shopping for administrative 51 services Availing of/shopping for professional 52 services Availing of/shopping for 53 government/public services Availing of/shopping for personal 54 services Availing of/shopping for medical and 55 health care services Shopping 6 Purchasing food and household 61 supplies (groceries) Purchasing clothes, shoes, personal 62 items Purchasing household appliances, 63 articles, equipment Purchasing capital goods (cars, houses, 64 etc.) Comparison shopping 65 Window shopping 66

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Sample Request for Proposals Template 73 Table 2. (Continued). Variable Primary Category Code Secondary Category Code Social/recreational 7 Communication/ correspondence 71 Socializing activities 72 Participating in religious/community/ 73 cultural events/activities Visiting entertainment and cultural 74 venues Indoor and outdoor sporting activities 75 Games/hobbies/arts/ crafts 76 Print/audio/visual media 77 Accompanying others/travel related 8 Accompanying children to places 81 Accompanying adults to places 82 Pick up or drop off other people/get 83 picked up or dropped off (private car, car/van pool, shuttle/limousine) Activities related to bus, public transit 84 and group rides (except car/van pool and shuttle/limousine) Change travel mode 85 Other (specify) 9 Not further defined (n.f.d.) 90 Means of Travel Car/van/truck driver 1 Car driver 11 (A4) Van driver 12 Truck driver 13 Car/van/truck passenger 2 Car passenger 21 Van passenger 22 Truck passenger 23 Motorcycle/moped 3 Motorcycle 31 Moped 32 Scooter 33 Bicycle 4 Bicycle 40 Walk/wheelchair 5 Walk 51 Skate/roller skate/ roller board 52 Motorized wheelchair 53 Non-motorized wheelchair 54 Bus/school bus 6 Regular bus 61 Intercity bus 62 Express bus 63 School bus 64 Train 7 Train 71 Trolley/streetcar 72 Taxi/shuttle 8 Taxi 81 Shared-ride taxi/jitney 82 Commuter van/shuttle bus: employer paid 83 Commuter van/shuttle bus: pay fare 84 Dial-a-Ride 85 Shuttle/limousine 86 Other (specify) 9 Other (specify) 90 Fuel Type Gasoline 1 Gasoline 10 Diesel 2 Diesel 20 LPG/LNG 3 LPG/LNG 30 Dual Fuel 4 Dual fuel 40 Other (specify) 9 Other (specify) 90 Employment Full-time 1 3545 hours 11 Status 4655 hours 12 Greater than 56 hours 13 Part-time 2 Less than 20 hours per week 21 Greater than 20 hours per week 22 Retired 3 Retired 31 Semi-retired 32 Full-time homemaker 4 Full-time homemaker 40 Unemployed seeking employment 5 Unemployed seeking employment 50 Unemployed not seeking employment 6 Unemployed not seeking employment 60 Full-time student 7 Full-time student 70 Child not in school/infant*to be 8 Child not in school/infant*to be 80 specified if skip mechanism not in place specified if skip mechanism not in place Volunteer work (unpaid) 9 Volunteer work (unpaid) 90 a Categories for Minimum and other Questions, Section 2.1.2

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74 Standardized Procedures for Personal Travel Surveys Table 3. Required question wording.a Question Recommended Standard for Question Wording Household Size (H3) "Including yourself, how many people live at this address? Please do not include anyone who usually lives somewhere else or is just visiting, such as a college student away at school. (If further clarification is needed, include infants and children, live-in domestic help, housemates, roomers.)" Number of Vehicles (H6) "How many vehicles are owned, leased, or available for regular use by the people who currently live at this address? Please be sure to include motorcycles, mopeds and RVs." (As clarification, regular use means "are in working order.") "How many bicycles in working condition are available to members of your household for use in their daily travel?" Owner or Renter Status (H7) "Do you own or rent your home? Own/buying (e.g. paying off a mortgage); Rent/lease; or Provided by job or military." Gender (P1) "Are you (is this person) male or female?" Disability (P11) "Do you have a disability or condition that has lasted 6 or more months and that makes it difficult to go outside the home alone, for example, to shop or visit a doctor's office?" Activity or Trip Purpose (A2) For work or work-related activities: Volunteer work should be specifically excluded from the definition; The clarification should be added that work means work for pay or profit; and Questions should be asked about a second job. When asking for activities, include a category "Other at-home activities." Number in Traveling Party "Including yourself, how many people were traveling with you? How many of these were (A6) household members?" If CATI is used, it is suggested that the follow-up question regarding number of household members only be asked when the household size is greater than one. At a minimum, the number in the traveling party should be asked whenever a private car, van, or truck is the mode of travel. Income "Please stop me when I get to the category that best describes the total combined income for everyone living at this address for last year:" Income response categories should match the start and end points used by the U.S. Census, although collapsing across income categories is acceptable. a Standard Question Wordings, Section 2.1.3. Table 4. Schedule of contacts and reminders. Steps Day Contact Content Received by Type Household 1 Advance letter Mail (R-7) Advance letter A week before recruitment is scheduled to commence 2 Recruitment (R) Telephone Recruitment interview Recruitment day 3 R+1 Mail Survey package sent out R+3 to R+5 4 Diary Day (D)-1 Telephone Pre-Diary Day reminder (motivation D-1 call) 5 D+1 Telephone Reminder to return completed survey D+1 (motivation call) 6 D+2 Mail Postcard reminder/reset of Diary Day to D+4 to D+6 D+7 7 D+6 Telephone Reminder and check on second D+6 opportunity for Diary Day 8 D+9 Mail Postcard reminder and reset of Diary D+11 to D+13 Day to D+14 9 D+13 Telephone Reminder and check on third D+13 opportunity for Diary Day 10 D+15 Mail Re-mailing of survey package and reset D+17 to D+19 of Diary Day to D+21 11 D+20 Telephone Reminder and check on fourth D+20 opportunity for Diary Day

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Sample Request for Proposals Template 75 The envelopes must be large, white envelopes (4 9.5 or larger), with the address printed directly onto the envelope, rather than using address labels; The envelope shall be printed with a recognizable return address on the envelope and an indication of the contents of the envelope (at least the survey name); and Postage stamps shall be affixed to the envelope, especially commemorative stamps, rather than using a franking machine or pre-printed bulk mail. To encourage higher response, the Contractor shall also Mail out a pre-notification letter that has been carefully formulated so that it is simple in language, appealing to a wide range of people, and clearly sets forth the importance of responding;8 and Provide detailed instructions in the form of an informational brochure or fact sheet.9 Care should be taken to ensure that the information is presented in an easy to read manner, with appropriate use of graphics where possible. Contractor will describe in the proposal recommendations for providing survey materials in languages other than English, and procedures for handling households that do not speak or write in English. Data-Collection Procedures Contractor will specify the data-collection procedures to be used (e.g., telephone recruitment with telephone or mailback retrieval, etc.). If using tele- phone retrieval, call-back attempts to any household must be limited to five or six attempts, and these attempts must be made at different times on different days.10 To ensure that later calculations of response rate are standardized, the Contractor must use at least the following four final disposition codes for households: 1. Complete interviews; 2. Eligible cases that were not interviewed (non-respondents); 3. Case of unknown eligibility; and 4. Ineligible cases.11 Table 5 presents a complete definition of households that are to be categorized in each dispo- sition code. The following protocol must be used for proxy reporting:12 1. For all persons, a code must be included in the database indicating whether the activity/travel report was provided directly by the individual conducting the activities or travel or by a proxy; 2. For persons aged 14 or less, activities/travel must be reported by a parent or other adult; 3. For persons aged 1517, proxy reporting is permitted, but direct reporting with parental permission is preferred; 4. All persons aged 18 or older must be asked directly for their activities or travel; and 5. The survey methods report must include the percent of adult respondents (persons aged 18 or older) whose activities or travel were reported by proxies (regardless of whether a completed diary was available), excluding from the denominator persons who were physically or men- tally unable to provide direct reporting at the time of retrieval (illness, incapacitation, etc.). It is desired that the Contractor's calling protocol include at least one call-back attempt to obtain a direct report from each adult household member aged 18 or older before accepting a proxy report. 8 Unit Non-Response, Section 2.2.6 9 Respondent Questions, Section 2.4.3 10 Number and Type of Contacts, Section 2.2.1 11 Computing Response Rates, Section 2.7.1 12 Proxy Reporting, Section 2.2.2

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76 Standardized Procedures for Personal Travel Surveys Table 5. Final disposition codes for RDD telephone surveys. Eligibility Disposition Recommended Code Eligible Interview 1.0 Complete 1.1 Partial 1.2 Eligible Non-Interview 2.0 Refusal and termination 2.10 Refusal 2.11 Household-level refusal 2.111 Termination 2.12 Respondent never available after call-back request 2.21 Telephone answering device (message confirms residential household) 2.22 Miscellaneous 2.35 Unknown Eligibility, 3.0 Non-Interview Unknown if housing unit 3.10 Not attempted or worked 3.11 Always busy 3.12 No answer 3.13 Telephone answering device (don't know if housing unit) 3.14 Telecommunication technological barriers, e.g., call blocking 3.15 Technical phone problems 3.16 Housing unit, unknown if eligible respondent 3.20 No screener completed 3.21 Other 3.90 Not Eligible 4.0 Out of sample 4.10 Fax/data line 4.20 Non-working number 4.31 Disconnected number 4.32 Temporarily out of service 4.33 Special technological circumstances 4.40 Number changed 4.41 Cell phone 4.42 Cell forwarding 4.43 Business, government office, other organization 4.51 Institution 4.52 Group quartersa 4.53 No eligible respondent 4.70 Quota filled 4.80 a If specified as ineligible in the survey design. To encourage a higher response rate, the Contractor shall provide incentives to households unless the pretest demonstrates that a response rate in excess of 70% may be achieved without an incentive.13 The incentives should Be offered only as pre-completion incentives, that is, be offered to all recruited house- holds in the sample and not offered conditional on respondents returning a completed survey; Be monetary in form and be small, on the order of $1$2 per person, except where local laws or ordinances prohibit offering money. In such cases, a small gift should be offered; and Be offered to each individual and not to the household as an entity. For a household to be deemed acceptable or "complete," the Contractor must provide the following data from that household: 1. Responses to all of the Minimum Questions listed in Table 1.14 13 Incentives, Section 2.2.8 14 Complete Household Definition, Section 2.2.3

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Sample Request for Proposals Template 77 2. Responses from at least one person from each of the following age groups represented in the household: 1517; 1864; 6574; and 75 and over.15 3. Sufficient information to geocode to latitude and longitude16: No less than 99% of household addresses, At least 95% of school and workplace addresses, and At least 90% of other locations. To encourage a higher response rate, the Contractor must provide a toll-free telephone num- ber for respondents to call to verify the survey's legitimacy and to ask questions.17 The Agency will also provide a telephone contact for respondent inquiries. For the same reasons, it is desired that the Contractor provide an Internet website with information about the survey, links to sponsor- ing agencies, answers to frequently asked questions, email and telephone contact for assistance or further information, and the ability to download survey materials. It is also desirable for the Con- tractor to provide respondents with online response capabilities. With regard to survey procedures, the Contractor shall adhere to the following standards, unless specifically exempted in the proposal: Contractor must provide a caller ID.18 When an answering machine is reached, Contractor shall leave messages according to the following protocol19: When an answering machine is reached on the initial recruitment/screening call, a mes- sage will be left at least once in the call rotation before classifying the number as non- responding; When an answering machine is reached on a reminder telephone call, a message will be left; and When an answering machine is reached during telephone retrieval of travel information, a message will be left. Contractor's telephone survey protocols must include a process for complying with call back requests, whether they occur in the recruitment or retrieval portion of a telephone survey.20 After the sixth request for a call back from the same household, the household may be categorized as a "soft" refusal and therefore eligible for Contractor's "soft refusal" conversion techniques.21 The Contractor shall exert extra effort to contact households that are difficult to contact. This may be done by increasing the number of calls for non-contacted units, designating specific times to call non-contacted units, expanding the data collection, and/or conducting face-to-face inter- views.22 It is desired that the Contractor include in the proposal the costs (separately) of, and an approach for, conducting a non-response survey. 15 Complete Household Definition, Section 2.2.3 16 Level of Geocoding to be Performed, Section 2.5.2 17 Respondent Questions, Section 2.4.3 18 Caller ID, Section 2.4.4 19 Answering Machines and Repeated Call-Back Requests, Section 2.4.5 20 Answering Machines and Repeated Call-Back Requests, Section 2.4.5 21 Answering Machines and Repeated Call-Back Requests, Section 2.4.5 22 Unit Non-Response, Section 2.2.6

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78 Standardized Procedures for Personal Travel Surveys Task 4: Interviewer Training and Quality Assurance In conducting the survey, the Contractor must ensure that the survey execution observes basic practice standards regarding ethics, which include23 The anonymity of the persons surveyed, and the confidentiality of the information they provide, must be protected at all times. A survey respondent may not be sold anything or asked for money as part of the survey. Persons must be contacted at reasonable times to participate in the survey and must be allowed to reschedule participation in the survey to a different time if that is more conven- ient for them. Survey personnel must be prepared to divulge their own name, the identity of the Con- tractor, the identity of the Agency, and the nature of the survey being conducted if requested by a respondent. Children under the age of 15 may not be interviewed without the consent of a parent or responsible adult. A respondent's decision to refuse participation in a survey, not to answer specific questions in the survey, or to terminate an interview while in progress must be respected if that is the respondents' firm decision. Respondents may not be surveyed or observed without their knowledge. Methods of data collection such as the use of hidden tape recorders, cameras, one-way mirrors, or invisible identifiers on mail questionnaires may only be used in a survey if the method has been fully disclosed to the respondent and the respondent agrees to its use. Contractor may not release research findings prior to the public release of the findings by Agency, unless the Agency has provided approval to do so. Contractor must ensure the reasonable safety of its fieldworkers during the execution of a survey. Contractor shall discuss its training program for interviewers, where interviewers are used, as Agency expects that all interviewers shall receive thorough and complete training.24 Validation Survey The Contractor shall conduct a validation survey that uses (at a mini- mum) the following three questions25: 1. Did you complete the initial survey? (yes or no). If "yes," go to Question 3 below. If "no," go to Question 2 below. 2. Did someone else in your household complete the survey? (yes or no). If "yes," go to Ques- tion 3 below. If "no," terminate the validation survey. 3. Question 3: Select a trip that the respondent is likely to remember from among the trips reported in the initial survey and note the time spent at the destination. Ask the respondent to recall the trip in question and to report the approximate time spent at the destination. The Contractor shall report a statistic indicating the percent of validated surveys that provided a negative answer to each of the first two questions or a mismatch on the third question.26 Agency has established as a "tolerable" level of failure on validation the following: 1% level of failure on the first two questions and 5% level of failure on the third question. 23 Ethics, Section 2.4.1 24 Unit Non-Response, Section 2.2.6 25 Validation Statistics, Section 2.7.5 26 Validation Statistics, Section 2.7.5

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80 Standardized Procedures for Personal Travel Surveys Table 6. Sample sizes required for specified levels of accuracy. Measure Assumed Desired Sample Measure Assumed Desired Assumed Sample Value Accuracy Size Value Accuracy Variance Size Response 50% 5% 384 Household 10 1 100 384 Rate 50% 10% 96 or 10 2 100 96 50% 15% 43 Person Trip 10 3 100 43 50% 20% 24 Rate 10 4 100 24 60% or 40% 5% 369 10 1 50 192 60% or 40% 10% 92 10 2 50 48 60% or 40% 15% 41 10 3 50 21 60% or 40% 20% 23 10 4 50 12 75% or 25% 5% 288 7 0.5 70 1076 75% or 25% 10% 72 7 1 70 269 75% or 25% 15% 32 7 1.5 70 120 75% or 25% 20% 18 7 2 70 67 Non-Response 10% 3% 384 7 0.5 50 768 to a 10% 5% 138 7 1 50 192 Question 10% 8% 54 7 1.5 50 85 10% 10% 35 7 2 50 48 20% 3% 683 4 0.4 40 960 20% 5% 246 4 0.8 40 240 20% 8% 96 4 1 40 154 20% 10% 61 4 1.5 40 68 30% 3% 896 4 0.4 16 384 30% 5% 323 4 0.8 16 96 30% 8% 126 4 1 16 61 30% 10% 81 4 1.5 16 27 Task 7: Conduct Survey Geocoding During the data collection process, the Contractor shall32 Collect and geocode information about frequently visited locations during the recruitment stages of the survey to maximize the opportunity to re-contact households later on to check addresses that cannot be matched. Perform the geocoding for non-household and non-habitually visited locations within a few days of data retrieval, also to allow households to be re-contacted if necessary. Ask respondents for the names of cross streets and/or landmarks during data retrieval. Use interviewers with a good knowledge of the survey area or provide interviewers with access to gazetteers containing accurate addresses for shopping centers and schools. Online address directories should be used to locate addresses in situations where supplementary information is not available. Any locations that cannot be geocoded to latitude/longitude must be referenced at least to a traffic analysis zone (TAZ) to avoid systematic bias.33 Where it is not possible to match out-of- region locations with a TAZ, such locations shall be assigned to a representative point outside the study area.34 Mail-back surveys must be edited immediately upon receipt so that respondents can be re-contacted to query missing or incorrect data times while the survey is still fresh in their memory.35 32 Geocoding Standards, Section 2.5.1 33 Level of Geocoding to be Performed, Section 2.5.2 34 Level of Geocoding to be Performed, Section 2.5.2 35 Item Non-Response, Section 2.2.5

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Sample Request for Proposals Template 81 Task 8a: Data Coding The data set as delivered by the Contractor shall be coded as follows36: All data fields must be filled with alphanumeric data (that is, blanks are not acceptable as a legitimate code). Missing data--whether as the result of a respondent refusal, an indication that the respon- dent does not know the answer, or a legitimate skip of the question--must receive a coded numeric value. These values shall be negative values and shall be -99 for a refusal. For "don't know" responses, it shall be -98. For legitimate skips or non-applicability of a question, the code shall be -97. In any question where a legitimate response could be zero, the code for that response must be the number zero (0). This will normally apply to any question requesting a count of elements. In like manner, the count that is the response will be the coded value in all cases. The person record must contain a count of the number of trips reported by the individual. In this variable, a count of 0 is to be used only to indicate the response that the person did not travel on the diary day. If no travel information was provided, then the value coded shall be -99. For questions to which the response is either "yes" or "no," the response of "yes" shall be coded as 1 and the response of "no" coded as 2. For response to the gender question, "male" shall be coded as 1 and "female" as 2. It is required that all variables be coded using multidigit, nested codes. For example, income shall be coded at least to the minimum coding levels and categories shown in Table 7.37 It is desired that trip purpose/activities be coded using the either the primary, secondary, or tertiary coding categories shown in Table 8.38 Contractor should specify the anticipated level in the proposal; however, the final level of coding will be determined jointly by the Con- tractor and Agency. Table 2 in this RFP section contains desired primary and secondary coding categories for the following complex variables39: Type of Dwelling (H2), Relationship (H4), Housing Tenure (H7), Education Level Attained (P10), Disability (P11), Race (P12), Vehicle Body Type (V1), Vehicle Ownership (V5), Trip Purpose (A2), Means of Travel (A4), Fuel Type, and Employment Status. Should Contractor propose a different coding approach for any of the above variables, one of the project deliverables will be a crosswalk to the desired coding categories in Tables 2, 7, and 8. In addition, data codes must be provided in the data set as follows: Time of day for data entry and storage shall be coded using two fields: one for the day num- ber and one for the time in military time (00:0023:59).40 36 Missing Values, Use of Zero, etc., Section 2.5.3 37 Coding Complex Variables, Section 2.5.4 38 Coding Complex Variables, Section 8.4 39 Coding Complex Variables, Section 2.5.4 40 Recording Time of Day, Section 2.4.7

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82 Standardized Procedures for Personal Travel Surveys Table 7. Coding for income categories. Minimum Detail Categories Minimum Coding More Detailed Categories More Detailed Coding Under $10,000 00 Under $5,000 000 $5,000$9,999 005 $10,000$19,999 01 $10,000 $14,999 010 $15,000$19,999 015 $20,000$29,999 02 $20,000$24,999 020 $25,000$29,999 025 $30,000$39,999 03 $30,000$34,999 030 $35,000$39,999 035 $40,000$49,999 04 $40,000$44,999 040 $45,000$49,999 045 $50,000$59,999 05 $50,000$54,999 050 $55,000$59,999 055 $60,000$69,999 06 $60,000$64,999 060 $65,000$69,999 065 $70,000$79,999 07 $70,000$74,999 070 $75,000$79,999 075 $80,000$89,999 08 $80,000$84,999 080 $85,000$89,999 085 $90,000$99,999 09 $90,000$94,999 090 $95,000$99,999 095 $100,000$109,999 10 $100,000$104,999 100 $105,000$109,999 105 $110,000$119,999 11 $110,000$114,999 110 $115,000$119,999 115 $120,000$129,999 12 $120,000$124,999 120 $125,000$129,999 125 $130,000$139,999 13 $130,000$134,999 130 $135,000$139,999 135 $140,000$149,999 14 $140,000$144,999 140 $145,000$149,999 145 $150,000 and over 15 $150,000 and over 150 Legitimate skip 97 Legitimate skip 97 Don't know 98 Don't Know 98 Refused 99 Refused 99 Start and end times for 24-hour diaries shall be 03:00 A.M. to 02:59A.M.41 (In the case of diaries that cover more than 1 day, end times are extended by 24 hours for each additional day.) An ID number shall be assigned to each eligible address or telephone number, and this number will remain attached to the person or household for the duration of the survey.42 If a stratified sample is used, it is desired that the ID number be stratification-based; date- based numbering is desirable for simple random or systemic samples.43 Should imputation be used in the final data set to substitute for missing data items or for values of data items that are known to be faulty, every inferred or imputed value shall be flagged.44 Contractors should note that any imputation procedure with the exception of overall mean imputation may be used. If hot-deck imputation is employed, it should be conducted without replacement. Task 8b: Interim Delivery of Data Agency requests interim delivery of data to permit periodic review and acceptance of the com- pleted households provided by the Contractor. This review is to be ongoing throughout the 41 Time of Day to Begin and End Reporting, Section 2.4.8 42 Creation of ID Numbers, Section 2.4.9 43 Creation of ID Numbers, Section 2.4.9 44 Missing Data Imputation, Section 2.6.3

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Table 8. Trip purpose/activity categories. Primary Code Secondary Categories Code Tertiary Categories Code Category Home 01 Sleeping/napping 011 Sleeping 0110 Preparing/eating 012 Preparing a meal/snack 0121 meals/snack/drinks Eating a meal/snack 0122 Other specified food-related activities 0129 Home 013 Indoor cleaning 0131 maintenance/cleaning Outdoor cleaning 0132 Gardening/ tending plants 0134 Care of textiles and footwear 0138 Other specified home maintenance and cleaning 0139 Household management 014 Paying household bills 0141 Budgeting, organizing, planning 0142 Selling, disposing of household assets 0143 Other specified household management 0149 Personal-care activities 015 Showering, bathing, personal grooming 0151 Health/medical care to oneself 0152 Receiving personal care from others 0153 Other specified personal-care activities 0159 Using computer/telephone 016 Using telephone (fixed line) (not including telephone 0161 shopping) Using cell phone (not including telephone shopping) 0162 Sending/reading/receiving email 0163 Internet browsing (not including online shopping) 0164 Shopping for goods and services using telephone 0165 (fixed line) Shopping for goods and services using cell phone 0166 Shopping for goods and services using Internet 0167 Other specified use of computer/telephone 0169 Caring for others 017 Caring for children 0171 Teaching, training, helping children 0172 Caring for adults 0173 Other specified caring for others 0179 Paid work 018 Paid work main job 0181 Paid work other job 0182 Other specified at home paid work 0189 Other specified at home 019 n.f.d. 0190 activities Work 02 Main job 021 Regular hours 0211 Overtime hours 0212 Extra hours (not paid as overtime) 0213 Other specified main job activities 0219 Other job 022 Regular hours 0221 Overtime hours 0222 Extra hours (not paid as overtime) 0223 Other specified job activities 0229 Work in internship, 023 Regular hours 0231 apprenticeship, etc. Overtime hours 0232 Extra hours (not paid as overtime) 0233 Other specified internship/apprenticeship activities 0239 Unpaid work in family 024 n.f.d. 0240 business Breaks and interruptions 025 n.f.d. 0250 from work Training and studies in 026 n.f.d. 0260 relation to work Volunteer work and 027 n.f.d. 0270 community services Looking for work/setting 028 Looking for work 0281 up business Looking for/setting up business 0282 Other specified work 029 n.f.d. 0290 related activities Education/ 03 Attendance at childcare 031 n.f.d. 0310 Childcare Attendance at school 032 n.f.d. 0320 Activities Attendance at college 033 n.f.d. 0330 Breaks/waiting at place of 034 n.f.d. 0340 general education Self study for distance 035 n.f.d. 0350 education course work (continued on next page)

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Table 8. (Continued). Primary Code Secondary Categories Code Tertiary Categories Code Category Homework, study, 036 n.f.d. 0360 research Career/professional 037 n.f.d. 0370 development training and studies Other specified activities 039 n.f.d. 0390 relating to education/childcare Eating Out 04 Restaurant/caf 041 Restaurant 0411 Caf/snack bar/cafeteria 0412 Fast food 042 Take out 0421 Eat in 0422 At friends' home 043 n.f.d. 0430 Picnicking 044 n.f.d. 0440 Other specified eating out 049 n.f.d. 0490 Personal 05 Availing of/shopping for 051 Post Office 0511 Business administrative services Other specified administrative service 0519 Availing of/shopping for 052 n.f.d. 0520 educational services Availing of/shopping for 053 Banking/credit union 0531 professional services Insurance 0532 Real estate 0533 Tax or accountant 0534 Legal services 0535 Other specified professional services 0539 Availing of/shopping for 054 n.f.d. 0540 government/public services Availing of/shopping for 055 Hairdresser/barber/beautician 0551 personal services Other specified personal service 0559 Availing of/shopping for 056 Medical 0561 medical and healthcare Dental 0562 services Eye care 0563 Physiotherapy 0564 Other specified healthcare service 0569 Availing of/shopping for 057 n.f.d. 0570 rental services Availing of/shopping for 058 n.f.d. 0580 repair and maintenance services Other specified activities 059 n.f.d. 0590 relating to personal business Shopping 06 Purchasing food and 061 n.f.d. 0610 household supplies (groceries) Purchasing clothes, shoes, 062 n.f.d. 0620 personal items Purchasing school 063 n.f.d. 0630 supplies Purchasing medical 064 n.f.d. 0640 supplies Purchasing household 065 n.f.d. 0650 appliances, articles, equipment Purchasing capital goods 066 n.f.d. 0660 (cars, houses, etc.) Comparison shopping 067 n.f.d. 0670 Window shopping 068 n.f.d. 0680 Purchasing other specified 069 n.f.d. 0690 goods. Social and 07 Communication/ 071 n.f.d. 0710 Recreational correspondence Activities Socializing activities 072 Doing activities/going to places and events together 0721 Receiving visitors 0722 Visiting friends and relatives 0723 Other specified socializing activities 0729

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Table 8. (Continued). Primary Code Secondary Categories Code Tertiary Categories Code Category Participating in 073 Participating in community celebration of 0731 religious/community/ historical/cultural events cultural events/activities Participation in non-religious community rites of 0732 weddings, funerals, births, etc. Participating in community social functions 0733 Participating in religious activities 0734 Participating in other specified 0739 religious/community/cultural activities Visiting entertainment and 074 Attendance at movies/cinema 0741 cultural venues Attendance at concerts 0742 Attendance at sporting events 0743 Attendance at library 0744 Attendance at amusement park 0745 Attendance at museum/exhibition/art gallery 0746 Attendance at zoo/animal park 0747 Attendance at other specified entertainment and 0749 cultural venues Indoor and outdoor 075 Organized sport 0751 sporting activities Informal sport 0752 Exercise (excludes walking) 0753 Walking, hiking, bushwalking 0754 Fishing, hunting 0755 Driving for pleasure 0756 Participation in other specified indoor and outdoor 0759 sporting activities Games/hobbies/arts/ crafts 076 Card, paper, board games, crosswords 0761 Gambling 0762 Arcade games 0763 Home computer games 0764 Hobbies, handwork, crafts 0765 Other specified activities relating to 0769 games/hobbies/arts/crafts Print/audio/visual media 077 Reading 0771 Watching/listening to television/video programs/radio 0774 Other specified activities using print, audio or visual 0779 media Other specified social and 079 n.f.d. 0790 recreational activities Accompan- 08 Accompanying children to 081 Accompanying children to receive personal services 0811 ying/helping places Accompanying children to receive medical/health 0812 others and services travel- Accompanying children to school, daycare centers 0813 related Accompanying children to sports lessons, etc. 0814 Accompanying children to other specified places 0819 Accompanying adults to 082 Accompanying adults to receive personal services 0821 places Accompanying adults to receive medical/health services 0822 Accompanying adults for shopping 0823 Accompanying adults for social activities 0824 Accompanying adults to cultural, sports, and 0825 entertainment venues Accompanying adults to other specified places 0829 Pick up or drop off other 083 Pick up someone or get picked up 0831 people/get picked up or Drop off someone or get dropped off 0832 dropped off (private car, car/van pool, shuttle/limousine) Activities related to bus, 084 Wait for/get on vehicle 0841 public transit, and group Leave/get off vehicle 0842 rides (except car/van pool and shuttle/limousine) Change travel mode 085 n.f.d. 0850 Other specified activity 089 n.f.d. 0890 related to accompanying others or travel-related No activity 09 No activity 091 n.f.d. 0910 No recorded activity 092 n.f.d. 0920 No further activity recorded 093 n.f.d. 0930 Other 99 n.f.d. 990 n.f.d. 9900

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86 Standardized Procedures for Personal Travel Surveys data-collection period. Ongoing review provides both Agency and the Contractor the opportu- nity to make mid-course corrections and manage expectations. Task 9: Delivery of Final Data Set Interim and final datasets shall be delivered in ASCII format, as portable SAS or SPSS files.45 If the travel data base contains two or more related files, the variables that link the files together must be in each file. The Contractor must provide the following data files at the conclusion of the survey for archival purposes: 1. The raw data files,46 2. The call-history files describing call dispositions during the recruitment process (if tele- phone recruitment was used),47 and 3. Partial data from incomplete households.48 Task 10: Analysis of Results The Contractor shall report response rates using the formula developed by the American Asso- ciation of Public Opinion Research (AAPOR), RR3A, as shown in Equation 1.49 The estimation of eligibility rate will be determined jointly by the Contractor and Agency. SR RR3 A = (1) ( SR + PI ) + ( RB + O ) + e A (UH + UO + NC ) where SR = number of complete interviews/questionnaires, PI = number of partial interviews/questionnaires, RB = number of refusals and terminations, O = other, NC = number of non-contacts, UH = unknown if household occupied, UO = unknown other, and eA = estimated proportion of cases of unknown eligibility that are eligible (AAPOR eligibil- ity rate: the same formula for calculating the eligibility rate is used). The Contractor will conduct a weighting and expansion exercise and shall include the weights in the data set along with a description of the weighting process in the metadata.50 The weights must include expansion factors so that the sum of the weights matches popula- tion estimates. The weighting and expansion process must follow the two-stage procedure described below. Stage 1 To establish household weights, Stage 1 of the weighting and expansion process should include the following steps: 1. Estimate an initial weight equal to the inverse of the design sampling rate. If dispropor- tional sampling is used, weights should be estimated for each stratum separately. The ini- tial weight of household i in stratum h is 45 Data Archiving, Section 2.6.4 46 Data Archiving, Section 2.6.4 47 Data Archiving, Section 2.6.4 48 Complete Household Definition, Section 2.2.3 49 Computing Response Rates, Section 2.7.1 50 Weighting and Expansion of Data, Section 9.2

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Sample Request for Proposals Template 87 1 w i ,exp = sh ,ih where wi,exp = initial weight (or expansion factor) for household i, and sh,ih = design sampling rate in stratum h of which i is an element. 2. If knowledge is available on levels of non-response in the survey at geographic or demo- graphic subdivision level, establish a weight to account for differential non-response. If non- response is not known at a level that subdivides the sample, assume the weight for this step is 1 and proceed to the next step. If the response rate is known at a level that subdivides the sample, the response weight for household i in subdivision j is 1 w i ,resp = rj ,ij where wi,resp = response weight for household i, and rj,ij = response rate in subdivision j of which i is an element. 3. Weight for difference in selection probabilities. This is necessary when the sample frame and the sampling unit do not coincide as, for example, when the sample frame is residential tele- phone numbers and the sampling unit is households. Households with more telephone lines are more likely to be selected under this system than households with fewer lines. The same applies if the sample frame is dwelling units and multiple households occupy some dwelling units. To account for these differential selection probabilities, the following weight should be applied to the households, where a one-to-one relationship between the sample frame and the households does not exist: 1 w i ,sel = ui where wi,sel = selection weight for observation i, and ui = number of times household i is represented in the sample frame.51 4. Obtain a composite weight for each household by multiplying the weights from the equa- tions in Steps 1, 2, and 3 together: w i = w i ,exp w i ,resp w i ,sel The weights identified for households in Stage 1 are also assigned to the persons and trips in the household. Stage 2 Separate weighting is conducted for households and persons. While the procedure used is similar, different variables are used in each weighting process. Final weights for households are identified by conducting the following steps: 1. Identify household variables for which population values are available (from external sources) and which also occur within the sample. The choice of variables should be dictated 51 Note that ui can range from a fraction for those households who share a dwelling or telephone line (or are episodic telephone owners) to values in excess of 1 when a household owns multiple telephone lines or inhabits more than one dwelling in the study area.

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88 Standardized Procedures for Personal Travel Surveys by the purpose of the survey, where bias is most expected, and the reliability of popula- tion values. 2. Break each variable into a manageable number of categories. The categories must be selected so as to ensure that the multidimensional "cells" that are produced by simultaneously cross- classifying all variables, all contain at least some sample values, because empty cells cannot be adjusted by weights and are, therefore, redundant. Individual cells can be collapsed into single larger cells to eliminate empty cells. 3. Sum household weights, established in Stage 1, in each cell. 4. Apply iterative proportional fitting to the cell weights identified above. The order in which the variables are considered in each iterative cycle is irrelevant since a unique solution is guar- anteed irrespective of the order of the variables. A closing error of no more than 1% on any marginal value is recommended. 5. Identify final weights by dividing the final cell weights above by the sum of the households in each cell. This is effectively dividing the weighted sum of households in each cell by the unweighted sum to produce a common weight for all households that belong in each cell. Note that while individual households had different weights at the end of Stage 1, households in the same cell now have the same weight. However, the effect of those individual weights did have an impact in structuring the seed n-dimensional matrix used in the iterative proportional fitting process employed here. The adjustments in Stage 2 represent a further improvement in Stage 1 weights, but, because cell totals are used in the process, individual weights are lost. 6. Transfer the final household weights to the data and include a description of the expansion and weighting process in the metadata. 7. Establish person weights in the same manner as was accomplished with household weights with the exception that person variables are used in the process and person weights from Stage 1 are used in the initial (seed) n-dimensional matrix. Final person weights are established by dividing the final cell values by the number of persons in each cell. 8. Establish trip weights by applying person weights to each trip. The sum of all trip weights in the sample will then represent the total number of trips made in the study area during the survey period although trip under-reporting will tend to result in this estimate being lower than the true number of trips conducted. Separate trip weights cannot be established because the true number of trips made in an area is unknown. Task 11: Final Report In addition to other data tables and information required by Agency, the final documentation must include the following information:52 Identification--clear identification of the sponsoring Agency(ies), the Contractor, and the name(s) of the Contractor's subcontractors and/or fieldwork agency(ies), if any. Survey purpose and objectives--description of why the survey is being conducted, what it hopes to achieve, and the expected results. Copies of the questionnaire and other survey documents--this includes the wording of all ques- tions including specific interviewer and respondent instructions and aids such as recruitment scripts, interview script (telephone and personal interview), maps, travel diaries, memory joggers, etc. These should be provided in an appendix. Other useful survey materials--interviewer instruction manuals, validation of results (tech- niques employed), codebooks, and incentive descriptions (monetary levels offered). Population and sampling frame--a description of the population that the survey is intended to represent as well as why this population was selected and a description of the sampling frame used to identify this population. 52 Documentation, Section 2.6.5

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Sample Request for Proposals Template 89 Sample design--a complete description of the sample design: sample size, sampling frame, information on eligibility criteria, and screening procedures. Sample selection procedures--methods by which respondents were selected by the Contrac- tor, details of how the sample was drawn, the levels of proxy reporting, what constituted a complete household, and the sample size. Sample disposition--refusals, terminations, ineligibles, completed interviews, and non- contacts. Also a description of the level of item non-response accepted for key variables and why. Response rates--how the eligibility rate for the unknown sample units was determined, a description of the AAPOR response rate formula used, as well as the calculation of the over- all response rate. Processing description--editing, data adjustment, and imputation procedures used. Precision of estimates--sampling error and include other possible sources of error to inform user of accuracy or precision and a description of weighting or estimating procedures. Basic statistics--a description of all base percentages or estimates on which conclusions are made. Data collection methods--survey mode and procedures. Survey period--dates of interviews of fieldwork or data collection and reference dates for reporting--that is, time, day, and date when calls or other forms of contact were made. Interviewer characteristics--number and background of fieldwork staff. Quality indicators--results of internal validity checks and any other relevant information such as external research. Contextual information--any other information required to make a reasonable assessment of the findings and data. Geocoding description--including how geocoding was conducted, the level of data imputa- tion and inference, and how these values are flagged, etc. The Contractor will assist the Agency in collecting the necessary organizational documenta- tion: the RFPs, proposal submission, contract and modifications, progress reports, key meeting results, key personnel costs, and information about situations that occurred during the survey period. The final report shall include the following as quality indicators: An overall estimate of item non-response that shall be calculated as the average item-non- response and expressed as a percentage to the following key questions53: Means of travel, Licensed driver status, Start time and end time of trip or travel time of trip, and Vehicle occupancy. Note that item non-response includes those items where values are missing, where the respondent has indicated that they "don't know" and where the respondent has refused to answer. The percent of non-mobile days.54 If questions are asked regarding the reasons why no travel occurred, as an advanced standard, the report must include analyses of these reasons and the characteristics of persons who reported no travel. An estimate of coverage error, calculated as the percentage deviation of the population of the study area estimated using the planned sample from that of the population of the same area 53 Item Non-Response, Section 5.5 54 Incorrect Reporting of Non-Mobility, Section 7.6

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90 Standardized Procedures for Personal Travel Surveys using a reliable external source. Coverage error must be estimated using the definition of coverage error in Equation 2 below55: F CE = 1 - x 100 (2) X% where CE = coverage error in percent, Fx = sample population multiplied by the inverse of the sampling rate, and ~ X = population from an external source. An assessment of sample bias, using the following procedure.56 The following variables should be used to test for bias: household size; vehicle availability; household income (if collected); race of each person in the household; age of each person in the household; and gender of each person in the household. The variables should be measured as follows: household size: mean value; vehicle availability: categories of 0, 1, 2, and 3+; household income: categories corresponding to those in Table 7; race: categories of white, black/African American, American Indian/Alaska native, Asian, Native Hawaiian/Pacific Islander, other single race, and two or more races; age: categories of 05, 610, 1114, 1517, 1864, 6574, 75 and over; gender: male and female. Total error should be measured using the percentage RMSE statistic defined in Equation 3: 2 rij - sij ni n ji 1 1 Percent RMSE = n rij 100 (3) ni i ji j where ni = number of variables i; nji = number of categories j in variable i; rij = reference value of variable i in Category j; sij = sample value of variable i in Category j. A data cleaning statistic (DCS), calculated using the following procedure57: N I count ( xi ,n ) DCS = n i N I where xi,n = ith data item of respondent n, { count ( x i ,n ) = 1 if i th data item of respondent n was cleaned 0 otherwise } 55 Coverage Error, Section 10.3 56 Assessing Sample Bias, Section 9.1 57 Data Cleaning Statistics, Section 2.7.6