Locating survey subjects begins with having sufficient information to find those that moved from their latest residence. Low-income households move at higher rates than the general population, and it seems reasonable to assume that within this group, welfare leavers will be the most mobile. Therefore, if surveys are going to become a routine part of the evaluation process, agencies should consider future evaluation needs in all their procedures. This includes changing intake procedures to obtain additional information to help locate subjects in the future and designing systems to allow access to other state administrative records. In the sections that follow, these presurvey procedures are discussed in more detail. This is followed by a description of the initial mail contact, which provides the first indication of whether a subject has moved. The section ends with a discussion of some tracing procedures that might be implemented if the subject is lost to the study.
As part of the intake process, or shortly thereafter (but perhaps separately from the eligibility process), detailed contact information should be obtained for at least two other people who are likely to know the subjects whereabouts and who do not live in the same household as the subject. In addition to name, address, and telephone number, the relationship of the contact to the subject should be determined along with his or her place of employment. We believe this step is crucial to obtaining acceptable response rates. This step also may be difficult to achieve because, in some situations, it may require a change in the intake system.
It is also useful to consider obtaining the subjects informed consent as needed to access databases that require consent at the same time as contact information is obtained. It is hard to state when and how consent might be used given the differences in state laws, but we assume that, at a minimum, state income tax records fall into this category (if they are assessable at all, even with consent). This is a common procedure on studies that track and interview drug users and criminal populations (Anglin et al., 1996).
Data to Be Provided to the Contractor with the Sample
In addition to the subjects name, address, telephone number, Social Security number, and all contact information, consideration should be given to running the subject through other state administrative databases (Medicaid, food stamps, etc.) prior to the survey. This may be particularly useful if the information in the sample file from which the sample is drawn is old or if the information in the files is different. Initial contacts should always start with the most recent address and telephone number. The older information is useful if a subject needs to be traced. The advantage of using the older information is that it might help to avoid unnecessary calls and tracing.
If the field period extends for a long period of time, it might be necessary to update this information for some subjects during the course of the survey.
Contacting Survey Subjects by Mail
Sending letters to prenotify the subject is accepted practice when conducting surveys (Dillman, 1978). It serves the dual purpose of preparing the subject for the telephone interview and identifying those subjects whose address is no longer valid. It is always iterative in a survey of this type. That is, each time a new address is located for a subject (through tracing as discussed later), an advance letter is sent prior to telephone contact.
If an envelope is stamped return service requested, for a small fee, the U.S. Postal Service will not forward the letter, but instead will affix the new address to the envelope and return it to the sender. This only works if (1) the subject has left a forwarding address and (2) the file is still active, which is usually just 6 months. If the letter is returned marked undeliverable, unknown, insufficient address, etc., additional tracing steps must be initiated.
Because the post office updating procedure is only active for 6 months, it is important to continue mail contacts with survey subjects if they are to be interviewed at different points in time. These mail contacts can be simple and include thoughtful touches such as a birthday card or perhaps a newsletter with interesting survey results.
Mailings should include multiple ways for the subject to contact the survey organization, such as an 800 number and a business reply post card with space to update name, address, and telephone numbers. Some small percentage will call and/or return the post card, negating the need for further tracing.
One of the problems with first-class letters is that the letters often do not reach the subject. The address may be out of date and not delivered to the correct household (e.g., Traugott et al., 1997), the letter may be thrown out before anyone actually looks at it, or the subject may open but not read the letter. To increase the chances that the subject does read the letter, consideration should be given to using express delivery rather than first-class mail. This idea is based on the logic that express delivery will increase the likelihood that the package will be opened by potential respondents and the contents perceived to be important. Express delivery may also provide more assurance that the letter has actually reached the household and the subject, particularly if a signature is required. However, requiring a signature may not produce the desired result if it becomes burdensome for the subject, for example, if the subject is not home during the initial delivery and needs to make special arrangements to pick it up. The annoyance may be lessened if, in addition to the letter, an incentive is enclosed.
Because express delivery is costly (but less than in-person contacts), it should be saved for those prenotification situations in which other means of contact have not been fruitful. For example, if first-class letters appear to be delivered, yet telephone contact has not been established, and tracing seems to indicate the address is correct, an express letter might be sent. It also might be used if the telephone number is unlisted or if the subject does not have a telephone. In these situations an express letter with a prepaid incentive might induce the subject to call an 800 number to complete the interview by telephone.
Tracing is costly. Tracing costs also vary quite a bit by method. As a general rule, it is best to use the least costly methods first when the number of missing subjects is greatest, saving the costlier methods for later when fewer subjects are missing. Database searches are generally the least costly at a few pennies a hit, while telephone and in-person tracing can cost hundreds of dollars a hit.
Two key components of a tracing operation are: (1) a comprehensive plan that summarizes the steps to be taken in advance, and (2) a case management system to track progress. The case management system should maintain the date and result of each contact or attempt to contact each subject (and each lead). The system should provide reports by subject and by tracing source. The subject reports provide tracers with a history and allow the tracer to look for leads in the steps taken to date. The reports should provide cost and hit data for each method to help manage the data collection effort. In the end it helps to determine those methods that were the most and least cost effective for searching for the population of interest, and this knowledge can be used for planning future surveys. Each of the tracing sources is discussed briefly in the following paragraphs.
Directory assistance (DA). Several DA services are now available. Accuracy of information from these services is inconsistent. DA is useful and quick, however, when just one or two numbers are needed. If the first DA attempt is not successful it may be appropriate to try again a few minutes later (with a different operator) or to try a different service. These calls are not free and the rates vary widely. Costs also include the labor charges of the interviewer/tracer making the calls.
Telephone lookup databases. There are several large telephone lookup services that maintain telephone directory and information from other sources in a database. These data are available by name, by address, or by telephone number. The search is based on a parameter determined by the submitter, such as, match on full name and address, match on last name and address, match on address only, or match on last name in zip code. Early in the tracing process the criteria should be strict, with matches on address only and/or address with the last name preferred. Later in the process broader definitions may be incorporated. Charges for database lookups are generally based on the number of matches found, rather than the total number of submissions. The cost is usually a few cents. These lookups are quick, generally requiring less than 48 hours, with many claiming 24-hour turnaround. However, the match rate is likely to be low. In a general population survey the match rate might be as high as 60 percent, and of those, some proportion will not be accurate. For a highly mobile, low-income population, where only those whose numbers are known to have changed are submitted, the hit rate is likely to be quite low. However, given the relatively low cost, even a very low match rate makes this method attractive.
Several companies provide this information, so one might succeed where another might fail. There also may be regional differences, with data in one area being more complete than in others. In California, for example, telephone numbers are often listed with a name and city, but no address. This limits the datas usefulness, especially for persons with common last names.
Specialized databases. These include credit bureaus and department of motor vehicles (DMV) checks where permitted. Checks with one or more of the credit bureaus require the subjects Social Security number, and they are more costly than other database searches. Charges are based on each request not the outcome of the request. More up-to-date information will be returned if the subject has applied for credit recently, which is less likely with a low-income population than the general population. DMV checks in many states, such as California, require advance planning to obtain the necessary clearances to search records.
Other databases. Proprietary databases available on the Internet and elsewhere contain detailed information on large numbers of people. Access to the databases is often restricted. However, these restrictions are often negotiable for limited searches for legitimate research purposes. Like credit bureaus, these files often are compiled for marketing purposes and low-income populations may not make the purchases necessary to create a record. Records on people often are initiated by simple acts such as ordering a pizza or a taxi.
Telephone tracers. For the purpose of this discussion, it is assumed that each telephone number and address that has been obtained for the subject has led to a dead end. This includes all original contact information and results from all database searches. At this point tracing becomes expensive. Tracers receive special training on how to mine the files for leads. People who have done similar work in the past, such as skip tracing for collection agencies, tend to be adept at this task. Tracers need investigative instincts, curiosity, and bullheadedness that not all interviewers possess. Tracers usually are paid more than regular interviewers.
The tracers task is to review the subjects tracing record, looking for leads, and to begin making telephone calls in an attempt to locate the subject. For example, online criss-cross directories and mapping programs might be used to locate and contact former neighbors; if children were in the household, neighborhood schools might be called; and employers, if known, might be contacted. Of course, all contact must be carried out discreetly. Some of these techniques are more productive in areas where community members have some familiarity with one another, generally places other than the inner cities of New York, Chicago, and Los Angeles. Nonetheless, even in urban areas, these techniques sometimes work.
Cost control is crucial in this process because much of the work is limited only by the imagination of the tracer (and tracers sometimes follow the wrong trail). Perhaps a time limit of 15 or 20 minutes might be imposed. At that time limit, the tracers work could be reviewed by a supervisor to determine if further effort seems fruitful, if another approach might be tried, or the case seems to have hit a dead end.
In-person tracing. This is the most expensive method of tracing, and it is most cost effective if it is carried out in conjunction with interviewing. Like telephone tracing, in-person tracing requires special skills that an interviewer may not possess and vice versa. For this reason it might be prudent to equip tracers with cellular telephones so that the subject, when located, can be interviewed by telephone interviewers. The tracer can thus concentrate on tracing.
Tracing in the field is similar to telephone tracing except that the tracer actually visits the former residence(s) of the subject and interviews neighbors, neighborhood businesses, and other sources. Cost control is more of a problem because supervisory review and consultation is more difficult but just as important.