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-- doctoral thesis --
Two Topics in Survey Methodology
Modelling the response process in establishment surveys proceeded thus far by adding steps of
operational character to the core cognitive steps of the individual cognitive model. Here (Paper
1) a larger unit of the cognitive analysis is posited: that part of the enterprise that is engaged in
responding to a survey, consisting of one or more employees, the tools they use and the established
practices of record keeping and survey responding. Propagation of representational states is the
key concept used for analysing the response process. A pilot study conducted on a survey of
schools (Paper 2) illustrates the ability of the approach to identify and suggest adjustment of
items of questionable accuracy and addresses the possibility of quantifying accuracy of collected
In order to assess the skewness of a nonprobability web sample in relation to the targeted
population, George Terhanian proposed a parallel availability of a probability sample from the
population and the use of the assessment to reweight data in the nonprobability sample. The
parallel availability of the two samples constitutes the double samples setup.
Propensity scores have been suggested as a way of adjusting web samples. Here (Paper 3)
the propensity score approach is broadened by (i ) putting it in a wider context of the double
samples setup applicable in other .elds as well, (ii ) showing the theoretical unbiasedness of the
estimator and (iii ) specifying the assumptions that need to hold. In a simulation, the effects of
the factors where an analytic approach was difficult or impossible to apply were investigated.
The paper also contains a simple example of applying the technique, with a step-by-step "how
Inference in the double samples setup proceeded thus far by modelling either the probabilities
of inclusion in the nonprobability sample or the study variable. A more general framework
is presented (Paper 4) that models both components at the same time. From the model an
estimator is derived. In a simulation, it is compared with three estimators that model just one
of the two components.
Finally, a nonparametric estimator for the situation of double samples is presented (Paper
5). Here, the values of the study variable. missing by design in the probability sample. are
imputed according to a distance measure on auxiliary information. The mean of a number of
closest units is imputed with the aim of reducing the variance of the estimator. For the case
of univariate auxiliary information treated in the study, an expression for the variance and a
variance estimator for this estimator is also presented and veri.ed in a simulation.
Keywords: response process, establishment surveys, socially distributed cognition, response
burden, measurement error, nonprobability samples, web surveys, double samples, propensity
scores, model-based estimation, imputation, nonparametric imputation, weighting.