Guidebook for Conducting Airport User Surveys (2009)

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137 Many of the issues related to planning and designing surveys of area businesses are common to other types of airport user surveys, and the reader will be referred to those sections of the guidebook where applicable. Note that “area businesses” are typically not restricted to private companies, but include gov- ernment departments and public institutions such as universities and health care providers. 9.1 Purpose of the Survey and the Data to Be Collected Surveys of area businesses and other organizations are undertaken for a number of reasons, such as the following: • Determining the importance of the airport to the business community for use in economic impact studies. • Collecting information on air travel needs for use in preparing cases to present to airlines to attract improved air services at the airport. • Collecting information on business travel characteristics, use of airports in the region for both commercial and business aviation, and desired improvements in aviation facilities and services. • Determining awareness of the facilities and services at the airport and the value of the airport to the community. As with all airport user surveys, the first step in conducting a survey of area businesses is to outline its goals and purpose. (See Chapter 2 for a discussion on specifying goals, defining the purpose of a survey, the importance of doing so, and who should be involved.) 9.2 Survey Methodology Surveys of area businesses and other organizations are perhaps the most difficult of all airport user surveys to perform in a way that gives results that accurately reflect the characteristics and views of the target population. The size and types of businesses, and their air travel requirements and use of airports in the area, vary widely from one business to another. Clearly defining the goals of the survey and the target population of businesses, selecting the appropriate sampling strategy and deciding how to handle non-responses are critical to producing reasonable results. Typically, all organizations in an area will compose the population of interest. To define a sample of these organizations, a list of all of them would ideally be developed, as—unlike air passengers—they cannot be sampled as they make use of the airport. Development of such a list can be difficult, if not impossible, and the surveyed population is often restricted to businesses for which contact information is readily available. C H A P T E R 9 Surveys of Area Businesses

138 Guidebook for Conducting Airport User Surveys Lists of businesses are often obtained by cooperating with local business organizations such as the board of trade, chamber of commerce, or economic development council or corporation. In some instances, such as studies to improve air service at the airport, the local business orga- nization may be a survey co-sponsor and will be willing to send the questionnaire out to its members. In other cases, local business organizations may be unwilling to burden their mem- bers with yet another survey. In these cases other sources, such as telephone directories, may have to be used. Four methods can be used in surveys of area businesses: • Mail—slow and typically gives a very low response rate. It can be more costly than an email/ Internet approach. Use of fax to send the survey request and return responses can reduce the time to conduct the survey and postage costs. However, because of the large amount of junk fax marketing, a fax request is unlikely to be answered unless it is sent to a specific individual. • Telephone—time consuming and costly, difficult to schedule interviews, and as a practical matter limits surveys to a sample of businesses, but response rates are better than mail or fax. A follow-up call may be required if the respondent has to look up an answer to a question. (Section 8.3 discusses telephone surveys in more detail.) • In-person—very time consuming and costly, difficult to schedule interviews, and as a prac- tical matter limits surveys to a smaller sample of businesses than telephone surveys, but can provide a better understanding of the issues and better response rates than mail or Internet surveys. When answers require research on the part of the respondent, a follow-up call may be required. • Internet—easiest and least costly, allows emailed survey requests to be easily forwarded to the appropriate person, and provides flexibility for respondents to complete the Web-based survey at a convenient time and answer the questionnaire in stages. It also facilitates easy follow-up of non-responses and eliminates data entry. Response rates can be low, but can be improved sig- nificantly with telephone contact before and/or after sending the request to participate in the survey. This approach can only be used if email addresses are available, but most business orga- nizations now collect the email addresses of their members. Each of these survey methods are discussed further in Section 2.2. Non-response can be a significant problem with surveys of area businesses, particularly mail and Internet surveys. If the purpose of the survey is to estimate air travel demand and character- istics, non-response is highly correlated with a business’s use of air travel. Businesses making lit- tle or no use of air travel will be much less likely to see any value in completing the questionnaire. When analyzing the results, assuming that non-respondents have the same air travel characteris- tics as responding businesses or assuming they do not make any air trips at all could lead to sig- nificant errors. This problem can be reduced, to some extent, by following up with a sample of non-respondents and asking them for general information about the size of their organization and use of air travel. Weighting of responses can be an issue due to the potential differences between large and small businesses. For example, in airport awareness studies, should all businesses be treated equally, or should large businesses be given more weight and, if so, by how much? Similar issues come up in other types of area business surveys for questions not scaled by the size of the business or level of air travel. For example, where businesses are asked “How critical is air service to your business?” should all businesses be weighted equally, or should larger businesses be given more weight? The weighting to be used should depend on the intended use of the results. For example, responses could be weighted by the number of local employees or results reported separately for organiza- tions of various size categories.

Surveys of Area Businesses 139 9.3 Sampling Methodology The first step in determining the sampling methodology will be to define the population of interest. Is it all businesses in the area, a particular industry segment, or just businesses that make use of the airport? The sampling method and sample size will depend on the survey method used. Using the Internet method in a small city, it may be possible to survey all businesses for which email addresses are available, but generally only a sample will be surveyed. The low response rates for Internet and mail surveys need to be taken into account when determining the sample size. For telephone or in-person interviews, the budget will usually only permit a survey of a pro- portion of area businesses. Given the wide range of businesses and their varying air travel requirements, businesses should be grouped and a stratified sample of businesses selected to sur- vey. Stratification should be based, if possible, on the type of business and number of local employees or some other measure of the size of the business. Unfortunately, data on businesses from business organizations do not always include a measure of the size of the business. If pos- sible, categories of businesses should be chosen so that they are comparable to categories used by other organizations or government departments (e.g., the North American Industry Classi- fication System codes of the U.S. Census Bureau) to allow comparison and sharing of data. Where stratified sampling is used, the proportion of businesses in each stratum (group) will gen- erally not be the same for all strata. As discussed in Section 3.3, the sampling fraction should be greater in strata with higher variation in the variables of interest within the stratum. For example, if interested in the numbers of air trips by employees of a business, the variation in the numbers of trips per employee will vary by type of business. Variation for consulting firms is likely to be much greater than for retail firms. Thus, for determining the total air trips by employees in the area, the proportion of consulting companies in the area surveyed should be higher than the proportion of retail firms. (Appendix B provides information on determining the sample size for each stratum.) Alternatively, sample sizes for each stratum could be set so that the level of accuracy in the variable of interest is similar in each stratum. For a categorical variable using random sampling within a stratum, Table 3-3 could be used to determine the sample size for each stratum. With strata based on the size of the business, there will be few very large businesses and many very small businesses and so a much higher proportion of the very large businesses will be required than of the very small businesses to obtain a similar level of accuracy.30 9.4 Questionnaire Wording and Length Questionnaires for surveys of area businesses should be kept short to maximize response rates. The time required to complete the questionnaire should not exceed about 20 minutes for busi- nesses where air travel is very important to the business and about 10 minutes in other cases. The questionnaire should be structured so that businesses that rarely or never use air service will only answer the first few questions. For Internet surveys, these questions could even be included in the email message so that businesses can respond with this information very easily. The questionnaire format, structure, and clarity, and the use of pre-tests are important con- siderations, as discussed in Chapter 2. To keep the questionnaire as short as possible, it is very important to match the questions to the purpose and goals of the survey, eliminating “nice to know” questions and focusing only on “need to know” information. 30 For example, if there are 10,000 businesses with fewer than 10 employees and 50 with more than 500 employees, to obtain similar accuracy in the two groups for a categorical question, 370 of the 10,000 very small businesses (3.7%) and 45 of the 50 large businesses (90%) would have to be surveyed to give an accuracy of ±5 percentage points.

140 Guidebook for Conducting Airport User Surveys Questions asked when surveying businesses are very different from the questions used in other airport user surveys, which typically survey individuals. In medium- and large-sized organiza- tions, for example, uncertainty can arise over which office or department should be responding to the survey. For business locations that are branches of a larger organization, the question word- ing should be clear as to whether information should be provided for the local branch or the whole organization. In general, branches of larger organizations should provide information for only the branch in question. Not only may the branch personnel not have the relevant data for other branches, but also this procedure will avoid double counting in the event that some of the other branches also respond to the survey. Another issue is whether any reasons given or opinions expressed are those of the person respond- ing to the survey or represent the position of the organization as a whole. While it may be desirable to obtain reasons or opinions for the organization, rather than the individual responding to the sur- vey, this might require a level of internal approval that would preclude a response. One potential solution is to ask the respondents to indicate their personal view of the organization’s position. In addition, questions should differentiate between commercial air service and corporate or charter services the business may use, since many medium- and large-sized businesses use sev- eral types of air transport. 9.5 Measures to Obtain Adequate Response Measures that should be taken to improve the response rate of surveys of area businesses include the following: • Market the survey. Seek the support of local business organizations and ask them to let their mem- bers know about the survey and why it is being performed, and encourage their participation. • In the introduction to the survey, include the name of the company or organization conduct- ing the survey and the survey sponsor, and make it clear what the survey is for, how the infor- mation being sought could benefit local businesses, and that all information provided will be treated as confidential and only released in aggregate form. • Keep the questionnaire short and avoid asking for information that is difficult to obtain; let respondents know that approximate numbers are sufficient. • Allow respondents adequate time to reply. The deadline for responding should allow sufficient time for people on vacation, leave, or work-related trips to respond when they return. Three weeks is a reasonable period, but longer may be advisable in July and August or around Christ- mas. Reminders should be sent weekly, with a final reminder within 48 hours of the survey’s closing time. • For Internet surveys: – Make a telephone call for the initial contact (if the budget permits) to explain the reason for the survey and identify the correct recipient. – Allow respondents to save a partially completed response and come back later to complete it. – Follow up non-responses and partially completed responses with emails and/or telephone calls. 9.6 Survey Budget The cost to conduct surveys of area businesses varies greatly with the survey method and the level and type of follow-up of non-responses. The topic of the survey and the support it receives from the business community are primary determinants of response rates.

The budget for Internet surveys of area businesses will include survey design and planning, including the development of a list of businesses; questionnaire design, testing and loading onto a survey website; follow-up of non-respondents; data checking and analysis; and reporting and presentation of findings. (See Chapter 2 for a more detailed discussion of the budget.) Costs for an Internet survey with 10 to 20 questions and an initial response rate (before follow- up) of 40% are approximately: • $10,000 for 100 businesses with only email follow-up of non-responses. • $15,000 for 100 businesses with telephone and email follow-up of non-responses. • $12,000 for 500 businesses with only email follow-up of non-responses. • $15,000 for 1,000 businesses with only email follow-up of non-responses. Costs could be less if there is good cooperation from local business organizations or the ini- tial response rate is higher. However, costs could be higher if additional follow-up and analysis of non-responses is required. Depending on the response rates, the results may be of limited value without such additional follow-up and analysis, especially if estimates of total population values are required. Costs for conducting telephone surveys of businesses increase almost proportionally with sample size and are roughly two to three times the values for Internet surveys, and costs for in-person interviews are even higher. 9.7 Summary Surveys of area businesses and other organizations are typically conducted to obtain data for economic impact studies, air service development, or airport awareness studies. The assistance of local business organizations is very beneficial in promoting the survey, providing lists of busi- nesses, and improving the response rate. Internet surveys are by far the most cost-effective means of conducting such surveys, with follow-up of non-respondents by email and, budget permitting, by telephone. Telephone surveys are another option. Although more costly, they will likely result in better quality data. All businesses should be included in Internet surveys. For telephone surveys, it will only be pos- sible to survey a sample of businesses, and a stratified sample that includes a higher proportion of large businesses should be used. Non-response can cause significant bias in the results. Measures should be taken to improve the response rate and collect at least minimal data, so that appropri- ate weights can be developed for the data analysis. Surveys of Area Businesses 141