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i Contents 1. INTRODUCTION....................................................................................................................................................1 2. LITERATURE REVIEW RESULTS.......................................................................................................................2 2.1 REVIEW OF THE STATE OF PRACTICE ...................................................................................................................2 2.1.1 Introduction.................................................................................................................................................2 2.1.2 Review of Recent Surveys............................................................................................................................2 2.1.3 NCHRP Synthesis of Highway Practice 236.............................................................................................10 2.1.4 TMIP Scan of Recent Travel Surveys ........................................................................................................15 2.1.5 Other Reviews ...........................................................................................................................................20 2.1.6 Impact of Technological and Social Changes on Travel Surveys .............................................................24 2.2 REVIEW OF RELEVANT STANDARDIZATION PROCEDURES .................................................................................31 2.2.1 Introduction...............................................................................................................................................31 2.2.2 Standards ..................................................................................................................................................32 2.2.3 Standardized Procedures ..........................................................................................................................36 3. IDENTIFICATION AND CATEGORIZATION OF POTENTIAL PROCEDURES AND ASSESSMENT MEASURES................................................................................................................................................................39 3.1 APPROACH.........................................................................................................................................................39 3.2 EVALUATION OF POTENTIAL AREAS FOR STANDARDIZATION............................................................................40 3.2.1 Categories of Classification......................................................................................................................41 3.2.2 The Rating Procedure ...............................................................................................................................41 3.2.3 Summary Table and Evaluation of Potential Areas for Standardization ..................................................42 4. DESIGN OF SURVEY INSTRUMENTS..............................................................................................................48 4.1 I-1: MINIMUM QUESTION SPECIFICATION ..........................................................................................................48 4.1.1 Definition ..................................................................................................................................................48 4.1.2 Research on Minimum Questions..............................................................................................................48 4.2 I-2: STANDARDIZATION OF CATEGORIES ...........................................................................................................52 4.2.1 Need for Standardization ..........................................................................................................................52 4.3 I-5: STANDARDIZATION OF QUESTION WORDINGS.............................................................................................54 4.3.1 Item Description........................................................................................................................................54 4.3.2 Review of Candidate Wordings .................................................................................................................54 5. DESIGN OF DATA COLLECTION PROCEDURES...........................................................................................65 5.1 D-1: NUMBER AND TYPE OF CONTACTS ............................................................................................................65 5.1.1 Definition ..................................................................................................................................................65 5.1.2 Review of Number and Type of Contacts ..................................................................................................65 5.2 D-3: PROXY REPORTING ....................................................................................................................................73 5.2.1 Definition ..................................................................................................................................................73 5.2.2 Effects of Proxy Reporting ........................................................................................................................73 5.3 D-4: COMPLETE HOUSEHOLD DEFINITION .........................................................................................................75 5.3.1 Description................................................................................................................................................75 5.3.2 Review of Complete Household Definitions ..............................................................................................76 5.4 D-6: SAMPLE REPLACEMENT .............................................................................................................................79 5.4.1 Issues in Sample Replacement...................................................................................................................79 5.4.2 Discussion, Review, and Analysis of the Issues.........................................................................................80 5.5 D-7: ITEM NON-RESPONSE ................................................................................................................................82 5.5.1 Definition ..................................................................................................................................................82 5.5.2 Analysis of Item Non-Response .................................................................................................................82 5.6 D-8: UNIT NON-RESPONSE ................................................................................................................................83 5.6.1 Definition of Unit Non-Response ..............................................................................................................83
ii 5.6.2 Review and Analysis of Unit Non-Response..............................................................................................83 5.6.3 Non-Response Follow-Up Study. ..............................................................................................................91 5.7 D-10: INITIAL CONTACTS ................................................................................................................................111 5.7.1 Item Description......................................................................................................................................111 5.7.2 Importance and Nature of Initial Contact ...............................................................................................111 5.8 D-13: INCENTIVES ...........................................................................................................................................113 5.8.1 Review of Incentives................................................................................................................................113 5.9 RESPONDENT BURDEN.....................................................................................................................................115 5.9.1 Definition ................................................................................................................................................115 5.9.2 Assessing Respondent Burden.................................................................................................................115 6. PILOT SURVEYS AND PRETESTS ..................................................................................................................119 6.1 P-2: REQUIREMENTS FOR PRETESTS OR PILOT SURVEYS .................................................................................119 6.1.1 Definition ................................................................................................................................................119 6.1.2 Review and Discussion............................................................................................................................119 6.2 P-3: SAMPLE SIZES FOR PRETESTS AND PILOT SURVEYS .................................................................................121 6.2.1 Description..............................................................................................................................................121 6.2.2 Analysis ...................................................................................................................................................121 7. SURVEY IMPLEMENTATION..........................................................................................................................125 7.1 E-2: ETHICS .....................................................................................................................................................125 7.1.1 Definition ................................................................................................................................................125 7.1.2 Review of Survey Ethics ..........................................................................................................................125 7.2 E-3: MAILING MATERIALS...............................................................................................................................125 7.2.1 Background .............................................................................................................................................125 7.2.2 Discussion and Review of Literature.......................................................................................................126 7.3 E-4: RESPONDENT QUESTIONS.........................................................................................................................128 7.3.1 Introduction.............................................................................................................................................128 7.3.2 Elements for a Consistent Approach.......................................................................................................128 7.4 E-5: CALLER ID...............................................................................................................................................130 7.4.1 Description..............................................................................................................................................130 7.4.2 Impact on Surveys ...................................................................................................................................130 7.5 E-9: ANSWERING MACHINES AND REPEATED CALL-BACK REQUESTS ............................................................132 7.5.1 Introduction.............................................................................................................................................132 7.5.2 Discussion of Issues ................................................................................................................................132 7.6 E-10: INCORRECT REPORTING OF NON-MOBILITY...........................................................................................134 7.6.1 Description..............................................................................................................................................134 7.6.2 Genuine and False Non-Mobility ............................................................................................................135 7.7 E-11: RECORDING TIME OF DAY......................................................................................................................137 7.7.1 Definition ................................................................................................................................................137 7.7.2 Discussion ...............................................................................................................................................137 7.8 E-12: TIME OF DAY TO BEGIN AND END REPORTING.......................................................................................137 7.8.1 Description..............................................................................................................................................137 7.8.2 Analysis ...................................................................................................................................................138 7.9 E-13: CREATION OF ID NUMBERS....................................................................................................................143 7.9.1 Introduction.............................................................................................................................................143 7.9.2 Need for Standardized Procedures..........................................................................................................143 8. DATA CODING INCLUDING GEOCODING...................................................................................................145 8.1 C-1: GEOCODING STANDARDS.........................................................................................................................145 8.1.1 Introduction.............................................................................................................................................145 8.1.2 Need for Standardized Procedures..........................................................................................................145 8.2 C-2: LEVEL OF GEOCODING TO BE PERFORMED...............................................................................................147 8.2.1 Description..............................................................................................................................................147 8.2.2 Discussion and Analysis..........................................................................................................................147 8.3 C-4: MISSING VALUES, USE OF ZERO, ETC. .....................................................................................................149
iii 8.3.1 Introduction.............................................................................................................................................149 8.3.2 Coding Issues ..........................................................................................................................................149 8.4 C-5: CODING COMPLEX VARIABLES ................................................................................................................150 8.4.1 Introduction.............................................................................................................................................150 8.4.2 Discussion and Analysis..........................................................................................................................150 9. DATA ANALYSIS AND EXPANSION .............................................................................................................165 9.1 A-1: ASSESSING SAMPLE BIAS.........................................................................................................................165 9.1.1 Definition ................................................................................................................................................165 9.1.2 Review and Analysis................................................................................................................................165 9.2 A-2: WEIGHTING AND EXPANSION OF DATA ...................................................................................................168 9.2.1 Definition ................................................................................................................................................168 9.2.2 Review and Analysis of Weighting Procedures .......................................................................................168 9.3 A-3: MISSING DATA IMPUTATION....................................................................................................................172 9.3.1 Introduction and Background .................................................................................................................172 9.3.2 Discussion of Imputation Procedures......................................................................................................172 9.4 A-4: DATA ARCHIVING....................................................................................................................................176 9.4.1 Definition of Archiving............................................................................................................................176 9.4.2 Potential Standardized Procedures for Archiving ..................................................................................176 9.5 A-6: DOCUMENTATION ....................................................................................................................................179 9.5.1 Introduction.............................................................................................................................................179 9.5.2 Review and Discussion of Standardizing Documentation.......................................................................179 10. ASSESSMENT OF QUALITY...........................................................................................................................185 10.1 Q-1: COMPUTING RESPONSE RATES ..............................................................................................................185 10.1.1 Background ...........................................................................................................................................185 10.1.2 Methods of Computing Response Rates ................................................................................................185 10.1.3 Standardizing Disposition Codes ..........................................................................................................198 10.2 Q-2: TRANSPORTATION MEASURES OF QUALITY...........................................................................................201 10.2.1 Definition ..............................................................................................................................................201 10.2.2 Potential Measures and Their Attributes...............................................................................................201 10.3 Q-3: COVERAGE ERROR.................................................................................................................................205 10.3.1 Definition ..............................................................................................................................................205 10.3.2 Potential as a Measure of Survey Quality.............................................................................................206 10.4 Q-5: PROXY REPORTING AS A QUALITY INDICATOR ......................................................................................208 10.4.1 Introduction...........................................................................................................................................208 10.4.2 Proxy Reporting as a Quality Measure.................................................................................................208 10.5 Q-6: VALIDATION STATISTICS .......................................................................................................................211 10.5.1 Definition ..............................................................................................................................................211 10.5.2 Design and Use of Validation Surveys ..................................................................................................211 10.6 Q-7: DATA CLEANING STATISTICS.................................................................................................................212 10.6.1 Definition ..............................................................................................................................................212 10.6.2 Data Cleaning and Its Use as a Quality Indicator................................................................................212 10.7 Q-8: NUMBER OF MISSING VALUES...............................................................................................................214 10.7.1 Definition ..............................................................................................................................................214 10.7.2 Missing Values as a Quality Indicator ..................................................................................................214 10.8 Q-9: ADHERENCE TO QUALITY STANDARDS AND GUIDELINES ......................................................................215 10.8.1 Background ...........................................................................................................................................215 10.8.2 Checklist of Quality Indicators .............................................................................................................215 11. REFERENCES ....................................................................................................................................................216
