Panel Care

To cope with panel attrition and to keep longitudinal response rates high, the SOEP has implemented “panel care” efforts to maintain personal contact between respondents and the survey. Panel care can be divided into incentives given directly to the respondent and other measures undertaken to keep the respondent in the study.

Respondents have been given gifts as tokens of appreciation since the very beginning of the study. Most of these gifts are small in-kind incentives like flowers, for which the interviewers have their own budget. In addition, the interviewers are asked to hand out a brochure with recent results from the study. Up to 2007, respondents also received a lottery ticket as a thank-you upon completion of their interview. Proceeds from the lottery benefit social projects in Germany. Since 2008, the lottery ticket has been included with the contact letter that is sent out about two weeks prior to the interview. It is thus given unconditionally, as long as the person participated in the previous wave. After a successful interview, the respondent receives a thank-you letter from survey institute along with one postage stamp as a small additional gift.

In 2009, different incentive schemes were tested in the new subsample I to increase the first-wave response rates. The basic experiment included four randomized groups of households: (1) those with the default setup of the conditional lottery ticket; (2) those with a “low” cash incentive of 5 euros per household and 5 euros per adult respondent; (3) those with a “high” cash incentive of 5 euros per household and 10 euros per adult respondent; and (4) those with a choice between a “low” cash incentive and a lottery ticket. The results showed slightly higher response rates in the cash groups, although the extra money in group (3) did not pay off. The current incentive strategy for the different SOEP samples is shown here:

Samples

A-H

J,K, L1, N, O, Q

L2, L3

P

Incentives for adults

Lottery ticket (5,427 households) and cash (636 households)

5 euros (households) and 10 euros (adults)

5 euros (households), 5 euros (adults), 10 euros (bonus payment)

5 euros donation to UNICEF(household)

Incentives for other respondents

Power bank (Youth Questionnaire), Bicycle repair kit (Early Youth Questionnaire), Small clock (Pupils Questionnaire CAPI/PAPI), Puzzle (Pupils Questionnaire MAIL)

Power bank (Youth Questionnaire), Bicycle repair kit (Early Youth Questionnaire), Small clock (Pupils Questionnaire CAPI/PAPI), Puzzle (Pupils Questionnaire MAIL)

5 euros (Youth Questionnaire), (Youth Questionnaire, Early Youth Questionnaire, Pupils Questionnaire) and 5 euros (Mother-Child Instruments)

The survey institute also does additional work to keep response rates high. Addresses are checked throughout the year to ensure that current addresses are on file. This is done, for instance, by sending out brochures about recent research based on the SOEP data and seasonal greeting cards.

Face-to-face interviews also ensure a personal relationship between interviewer and respondent, which increases the likelihood that respondents will stay in the survey. Keeping the same interviewer over time is therefore an important goal of the survey. Some SOEP respondents have in fact had the same interviewer since the beginning in 1984.

Last change: May 04, 2021