Articles/Chapters

Joop J. Hox, Edith D. de Leeuw and Eva A. O. Zijlmans, ‘‘Measurement Equivalence in Mixed Mode Surveys’’, Frontiers in Psychology, 5 February 2015, http://dx.doi.org/ 10.3389/fpsyg.2015.00087. Surveys increasingly use mixed mode data collection (that is, combining face-to-face and Web) because this controls costs and helps to maintain good response rates. However, a combination of different survey modes in one study, be it cross-sectional or longitudinal, can lead to different kinds of measurement errors. For example, respondents in a face-to-face survey or a Web survey may interpret the same question differently, and might give a different answer, just because of the way the question is presented. This effect of survey mode on the question-answer process is called measurement mode effect. This study develops methodological and statistical tools to identify the existence and importance of mode effects in a mixed mode survey. In addition, it assesses the magnitude and importance of mode effects in measurement instruments using a specific mixed mode panel survey (Netherlands Kinship Panel Study or NKPS). Most measurement instruments in the NKPS are multi-item scales, therefore confirmatory factor analysis (CFA) will be used as the main analysis tool, using propensity score methods to correct for selection effects. The results show that the NKPS scales by and large have measurement equivalence, but in most cases only partial measurement equivalence. Controlling for respondent differences on demographic variables, and on scale scores from the previous uni-mode measurement occasion, tends to improve measurement equivalence, but not for all scales. The discussion ends with a review of the implications of these results for analyses employing such scales. This article is part of a thematic dossier on ‘‘Measurement Invariance’’, edited by R. van de Schoot, P. Schmidt and A. de Beuckelaer (see the ‘‘Brochures’’ section of this issue of the BMS).