- Non response is an error of observation
- Error introduced to survey estimate is a function of percentage of sample not responding to survey, and differences on the statistic between respondents and non respondents.
- Can be variable component: eg interviewer effect
Non Response Rates
- Components of unit non response
o Whether all units in sampling frame are eligible for survey
§ Eg, in area probability samples of minority groups, many sample households may be ineligible for survey because no minority group members live there.
o Whether each unit sampled contains one sample element or many.
o Whether all sample persons have same probability of selection.
o Whether substitution at sampling stage is permitted
- Non observation of sample units
- Classification of outcomes
- Response rate calculation
Temporal Change in Response Rates
Item Missing data
- Statistical models for non-response
o Callback models with double sampling
§ Probability sample of remaining non respondents is drawn, and then interviewed à used to estimate characteristics of all respondents
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