5. Conclusions
The paper has found that there do appear to be within household and within
individual correlations for missing income data. Also, unlike other papers, we do not
find interviewer effects. Female interviewers are no more successful than male
interviewers in getting responses to income questions from main respondents and
their partners. We must bear in mind, however, that this lack of association could be
affected by the processes that lead to male and female interviewers being assigned
to particular respondents.
We also find that there is a systematic tendency for income data to be missing at
sweeps one and two over and above what we know about unit and partner non-
response. For both the main and partner respondents income non-response is
consistently related to self-employment. This suggests that how income questions
are asked to the self- employed may need to be considered in more detail. At sweep
one, both main and partner respondents in Northern Ireland are less likely to respond
to the income questions. At sweep two, previous income non-response at sweep
one and maintaining the same respondents are important predictors of non-
response.
Finally, attrition at sweep two does appear to be related to both family income at
sweep one, in that low income respondents are more likely to drop out at sweep two,
as well as previous item non response to income questions at sweep one.
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