Interview schedule and fielding periods
In the initial survey plan, respondents from each of the four Original Cohorts were to be interviewed yearly over a five-year period. However, due to cost considerations, it was decided after the second survey of the Older Men to survey the two older groups (Older Men and Mature Women) biennially rather than annually. In order to permit a survey at the end of the five-year period, Mature Women respondents were interviewed in both 1971 and 1972. Due to their greater mobility, the Young Women and Young Men were interviewed annually.
A decision was made at the end of the first five-year period to continue the interviews for another five years because of the usefulness of these data and the relatively small sample attrition. At this point, the interviewing pattern changed to a 2-2-1 schedule; each respondent was contacted by phone approximately every two years, then again in person one year after the second phone interview. The 2-2-1 schedule was continued through 1988 for the Young Women and 1987 for the Mature Women, when the decision was made to conduct a personal interview every other year. However, the implementation of the biennial schedule was interrupted by the 1990 decennial Census. Thus, the scheduled 1990 Young Women survey was pushed back to 1991.
Tables 1a and 1b depict the years in which each cohort was surveyed, the type of interview used, the fielding period, and the number and percent of respondents with completed interviews. Users should note that, in years during which the survey was conducted in person, some interviews were administered by telephone when necessary.
| Year | Primary Type of Interview Note 1a.1 |
Fielding Period | Total Interviewed | Retention Rate Note 1a.2 |
Retention Rate, Living Respondents Only Note 1a.3 |
|---|---|---|---|---|---|
| 1967 | Personal | May-July | 5083 | 100.0% | 100.0% |
| 1968 | May-July | 4910 | 96.6% | 97.0% | |
| 1969 | Personal | May-July | 4712 | 92.7% | 93.3% |
| 1971 | Personal | April-June | 4575 | 90.0% | 91.0% |
| 1972 | Personal | April-June | 4471 | 88.0% | 89.3% |
| 1974 | Telephone | April-June | 4322 | 85.0% | 86.7% |
| 1976 | Telephone | April-June | 4172 | 82.1% | 84.2% |
| 1977 | Personal | April-June | 3964 | 78.0% | 80.3% |
| 1979 | Telephone | April-June | 3812 | 75.0% | 77.8% |
| 1981 | Telephone | April-June | 3677 | 72.3% | 75.8% |
| 1982 | Personal | July-September | 3542 | 69.7% | 73.4% |
| 1984 | Telephone | April-June | 3422 | 67.3% | 71.8% |
| 1986 | Telephone | July-September | 3335 | 65.6% | 71.1% |
| 1987 | Personal | July-September | 3241 | 63.8% | 69.5% |
| 1989 | Personal | June-August | 3094 | 60.9% | 67.6% |
| 1992 | Personal | October-December | 2953 | 58.1% | 66.6% |
| 1995 | Personal | June-September | 2711 | 53.3% | 63.5% |
| 1997 | Personal | July-September | 2608 | 51.3% | 63.7% |
| 1999 | Personal | June-August | 2467 | 48.5% | 62.4% |
| 2001 | Personal | June-August | 2318 | 45.6% | 61.8% |
| 2003 | Personal | June-August | 2237 | 44.0% | 62.2% |
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Note 1a.1: Even in years during which the survey was conducted in person, some interviews were administered by telephone when that was the best way to complete a case. |
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Note 1a.2: Retention rate is defined as the percent of base-year sample members who were interviewed in any given survey year. Included in the calculations are deceased and institutionalized sample members, as well as those serving in the military. |
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Note 1a.3: This retention rate excludes sample members known to be deceased in each survey year. |
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| Year | Primary Type of Interview Note 1b.1 |
Fielding Period | Total Interviewed | Retention Rate Note 1b.2 |
Retention Rate, Living Respondents Only Note 1b.3 |
|---|---|---|---|---|---|
| 1968 | Personal | January-March | 5159 | 100.0% | 100.0% |
| 1969 | Personal | January-March | 4930 | 95.6% | 95.6% |
| 1970 | Personal | January-March | 4766 | 92.4% | 92.5% |
| 1971 | Personal | January-March | 4714 | 91.4% | 91.6% |
| 1972 | Personal | January-March | 4625 | 89.6% | 90.0% |
| 1973 | Personal | January-March | 4424 | 85.8% | 86.1% |
| 1975 | Telephone | January-March | 4243 | 82.2% | 82.7% |
| 1977 | Telephone | January-March | 4108 | 79.6% | 80.1% |
| 1978 | Personal | January-March | 3902 | 75.6% | 76.1% |
| 1980 | Telephone | January-March | 3801 | 73.7% | 74.3% |
| 1982 | Telephone | January-March | 3650 | 70.8% | 71.4% |
| 1983 | Personal | January-March | 3547 | 68.8% | 69.4% |
| 1985 | Telephone | January-March | 3720 | 72.1% | 72.9% |
| 1987 | Telephone | January-March | 3639 | 70.5% | 71.5% |
| 1988 | Personal | May-July | 3508 | 68.0% | 69.1% |
| 1991 | Personal | May-August | 3400 | 65.9% | 67.3% |
| 1993 | Personal | September-November | 3187 | 61.8% | 63.2% |
| 1995 | Personal | June-September | 3019 | 58.5% | 60.2% |
| 1997 | Personal | June-September | 3049 | 59.1% | 61.3% |
| 1999 | Personal | June-August | 2900 | 56.2% | 58.9% |
| 2001 | Personal | June-August | 2806 | 54.4% | 57.5% |
| 2003 | Personal | June-August | 2859 | 55.4% | 59.0% |
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Note 1b.1: Even in years during which the survey was conducted in person, some interviews were administered by telephone when that was the best way to complete a case. |
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Note 1b.2: Retention rate is defined as the percent of base-year sample members who were interviewed in any given survey year. Included in the calculations are deceased and institutionalized sample members, as well as those serving in the military. |
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Note 1b.3: This retention rate excludes sample members known to be deceased in each survey year. |
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Important information: Interview modes
Although each of the personal interviews contains data of roughly the same degree of completeness, data gathered during the telephone interviews were not meant to update the longitudinal record of a respondent. Rather, the telephone interviews were intended to obtain a brief update of information on each respondent and to maintain sufficient contact so that the lengthier personal interview could be completed. The combination of fluctuating fielding periods and type of interview (i.e., personal or phone) may affect not only the probability of reinterview but also the reference periods of time-related questions.
There is another source of inconsistency with respect to time references. A given year's survey instrument may use the previous calendar year as a reference period for some questions, while other questions will collect data for the year since last interview. Income data, for example, were often collected for the calendar year, corresponding to the time frame for a respondent's tax records; employment data were usually collected for the year since the last interview. In most cases the variable titles will indicate the time period covered.
Interview methods
Listings of respondents to be interviewed were generated by the Census Bureau and distributed to its 12 regional offices. Current addresses and contact information were generated from data collected during the last interview and through a postal check conducted by Census. Cases were assigned to interviewers who lived in the same geographic area as the respondent. Interviewers then received copies of the questionnaire (or a laptop computer for computer-assisted personal interviews (CAPI)) and (if used) respondents' Household Record Cards and flashcard and/or information booklets.
In each survey round, interviewers were responsible for contacting each respondent in their caseload and for using additional local level resources to locate those respondents who had moved since the last interview. Respondents who had moved outside the geographic district of their original interviewer were assigned to another unless there were no personnel nearby. In the latter event, an effort was made to interview the respondent by telephone.
Each respondent to be interviewed was sent various materials designed to encourage continued participation. Advance letters thanking respondents for taking part in the interviews and informing them of the coming survey were mailed prior to each interview period. Fact sheets highlighting recent research findings from each cohort's survey data were also provided. Respondents who had initially refused to participate in a survey were sent letters and some additional materials by the regional offices designed to encourage their continued participation and were once again contacted by local level interviewers to secure the interview.
While the type of survey, personal or telephone, determined the chief mode of contact, an alternate contact method was used for certain respondents. During a personal survey, for example, those respondents who lived long distances from the Census interviewer's base of operation or those for whom the Census supervisor has decided that another contact method was warranted were contacted by telephone. Although survey instruments are written in English only, multilingual interpreters were made available by the regional offices to interviewers who needed them.
Beginning in 1995, respondents in the two women's cohorts were interviewed during the same time period; a single computer-assisted personal interview (CAPI) replaced the separate paper-and-pencil interview (PAPI) instruments used during the previous interviews. While data were collected simultaneously for the two cohorts, they were released separately by cohort. This CAPI interview continued on a biennial basis through 2003 when the survey ended.
The average length of an interview varied depending on the type conducted, with personal PAPI interviews lasting 50-60 minutes, telephone PAPI interviews averaging 20-25 minutes, and CAPI interviews lasting about 70 minutes. As a validation check, a percentage of the respondents were contacted following the interviews to ascertain that the interviews had taken place. No stipends were paid to Original Cohort respondents for their participation until 2003. During the 2003 fielding, a special incentive experiment was conducted to see how a subset of respondents responded to being offered money to participate. Variables associated with this incentive experiment are R65017.00, R76056.00-R76060.00, R76105.10, and R76105.20.