Respondent behavior and data quality aspects in panel surveys : four empirical contributions

The four essays of this dissertation provide a number of new and unique
insights on diverse issues of respondent behavior and aspects of data quality in
surveys.
The first paper examines the determinants of item nonresponse on several
questions of households' wealth, households' income, and respondents' income. It
firstly provides empirical evidence that the mechanisms behind item
nonresponses and "don't know" statements differ. The item nonresponse intensity
is found to be item specific. The interactions between the respondent and the
interviewer and the interview situation are evaluated and it is found that the
gender of both, respondent and interviewer, and the age difference between
interviewer and respondent have an influence on the occurrence of nonresponse.
The second and third paper show that the correlation of item nonresponse with
subsequent unit nonresponse is not necessarily positive and linear. The analysis
shows a negative correlation of item nonresponse with the newly introduced
category of (wealth-) questionnaire nonresponse. With respect to subsequent unit
nonresponse it is shown that the correlation pattern with the INR rate is
nonlinear. It obeys an inverse-U-shaped pattern, which is explained by
simultaneous drop-out of two types of respondents: those with low INR
propensity and those with high INR propensity.
Finally, the fourth study examines the quality of income data provided by the
respondents with respect to rounding. It finds that rounding does not occur at
random, but is explicable by cost/benefit considerations of the respondent. The
magnitude of rounding is also correlated with the income figure and
autocorrelated. This provides evidence that the rounding error is likely to harm
estimates of empirical studies with rounded data. From a methodological point of
view, this study contributes to the check of ordinality of discrete outcomes of a
variable and the adequacy of ordered regression models.
All four papers of this dissertation contribute to the understanding of the social
interaction processes which occur during a survey interview. The benefit of the
insights provided in this dissertation is threefold: first, the findings enable survey
institutions to advance the data collection process, in order to reduce data
deficiencies and increase the informational value of the survey: We have shown
that pairing interviewers based on gender and age may reduce income INR, Face-to-face interviews are beneficial for reducing INR and UNR, and experienced
interviewers improve the quality of the collected data.
Second, the results could support the sophistication of imputation procedures
for missing or misreported data. Since we have shown that the mechanisms
behind item nonresponses and "don't know" statements originate from different
response processes, the origin of missing statements should be considered by
imputation methods.
Third, the methods employed in the studies may improve researchers' ability
to rigorously deal with misreports in his or her own empirical analyses, e.g. to
use selection models with pre-interview data as instruments.
Nonetheless, further research is needed to derive more concrete advise on how
to design a survey study to increase the quality of the data collected. Since the
approach underlying the studies herein is of empirical nature, the results of these
studies are restricted to observable and surveyed characteristics of respondents,
interviewers and the interview situation. It is likely that this reflects only part of
the story, since a lot of possible determinants may be unobservable, nonmeasurable
or not surveyed. This opens avenues of qualitative research in the
disciplines of e.g. sociology and psychology.