Editing Concept testing (section)

==Questionnaires==

It is important that the instruments (questionnaires) to test the product have a high quality themselves. Otherwise, results from data gathered surveys may be biased by measurement error. That makes the design of the testing procedure more complex. Empirical tests provide insight into the quality of the questionnaire. This can be done by:
* conducting [[cognitive pretesting|cognitive interviewing]]. By asking a faction of potential-respondents about their interpretation of the questions and use of the questionnaire, a researcher can verify the viability of the cognitive interviewing.
* carrying out a small pretest of the questionnaire, using a small subset of target respondents. Results can inform a researcher of errors such as missing questions, or logical and procedural errors.
* estimating the measurement quality of the questions. This can be done for instance using test-retest,<ref>Lord, F. and Novick, M. R.(1968). Statistical theories of mental test scores. Addison – Wesley.</ref> quasi-simplex,<ref>Heise, D. R.(1969). Separating reliability and stability in test-retest correlation. American Sociological Review, 34, 93-101.</ref> or mutlitrait-multimethod models.<ref>Andrews, F. M. (1984). Construct validity and error components of survey measures: a structural modelling approach. Public Opinion Quarterly, 48, 409-442.</ref>
* predicting the measurement quality of the question. This can be done using the software Survey Quality Predictor (SQP).<ref>Saris, W. E. and Gallhofer, I. N. (2014). Design, evaluation and analysis of questionnaires for survey research. Second Edition. Hoboken, Wiley.</ref>