Basic Monthly Survey Methodology and Documentation Page
Each month, Bureau of the Census field representatives attempt to collect data from the sample units during the week of the 19th. For the first month-in-sample interview, the interviewer visits the sample address to determine if the sample unit exists, if it is occupied, and if some responsible adult will provide the necessary information. If someone at the sample unit agrees to the interview, the interviewer uses a laptop computer to administer the interview.
More than 90 percent of month-in-sample 2 through 4 and 6 through 8 interviews are conducted by telephone. Interviewers continue to visit households without telephones, with poor English-language skills, or which decline a telephone interview. Approximately 15 percent of the sample each month is interviewed by telephone from one of three centralized telephone interviewing centers: Hagerstown, Maryland; Jeffersonville, Indiana; and Tucson, Arizona. Interviewing at these centers begins on Sunday afternoon of interviewing week and ends on Wednesday. Cases which have not been contacted at this point are transferred to the field staff, either for telephone or personal visit interviews. Field interviewers have until Tuesday of the following week to complete all their assigned cases.
A typical field representative's workload consists of about 37 sample addresses, some of which may be nonexistent or vacant. One of the most difficult tasks an interviewer faces is obtaining respondent cooperation. In some cases, finding someone at home the first (or fifth) month-in-sample may require the interviewer to visit the area several times. CPS is a voluntary survey, and persuading residents to take the time to answer questions completely and as accurately as possible is sometimes a difficult challenge. Despite these difficulties, interviewers usually obtain responses from more than 93 percent of their eligible cases. This, of course, varies by type of area and the mix of telephone versus personal visit interviewing.
The interview begins with questions about the housing unit and the people who consider this address their usual residence. Basic demographic information is collected for each household member. Labor force information is collected for each civilian 15 years of age or older, although the data for 15-year olds are not used in official BLS estimates. After the labor force information has been collected for all eligible household members, supplemental questions particular to that month's interview may be asked of specific family members or the entire household. In most cases, the interviewer will conduct subsequent interviews by telephone and will not actually visit the sample unit again until the fifth month-in-sample interview, the first interview after the 8-month resting period.
The specific questions to be asked appear on the computer screen, and the interviewer has been trained to ask each question exactly as it is worded. Based upon the response entered by the interviewer, the computerized questionnaire (or data collection instrument) determines the next question to be asked. While some questions require simple "yes" or "no" responses, others require the interviewer to categorize a response into a set of predetermined categories. Occasionally, interviewers type in answers directly, rather than selecting predetermined categories, although, with the exception of the responses to questions about the name of an employer, job duties, and occupation, the interviewer rarely has to type a lengthy response.
In subsequent interviews, information collected in previous interviews is used to shorten portions of the interview and reduce spurious month-to-month changes. For example, instead of relisting the household members, the interviewer verifies if all who were listed previously still reside at the address, and if anyone has moved into the unit. Similarly, employed persons who verify they are still working for the same employer are asked if their job duties have changed and if the description of their job last month is accurate, rather than having this information reasked each month.
Interviewer's Manual, Pt A2, Conducting the CPS Interview
Basic Monthly Survey Methodology and Documentation Page
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