Mechanisms of Panel Conditioning in Longitudinal Studies: Reflection, Satisficing, and Social Desirability (PaCo)

A Joint Research Project by GESIS, ZPID, and Utrecht University

Project Description

The project “Mechanisms of Panel Conditioning in Longitudinal Studies: Reflection, Satisficing, and Social Desirability” is a joint research project realized in cooperation with GESIS – Leibniz Institute for the Social Sciences and Utrecht University that addresses the problem of panel conditioning effects – a measurement error in longitudinal studies that threatens the validity and quality of panel data.

Longitudinal surveys in general are highly relevant to research across disciplines. They allow researchers to study intra-individual stability and change over time and to make statements about causal relationships. By now, Germany hosts multiple large panel infrastructures of national and international importance. Nevertheless, concerns about their quality have been raised along with the request to intensify methodological research to provide information on the quality of panel data and their susceptibility to bias (Leopoldina 2016). The PaCo-project aims to comprehensively investigate the magnitude of bias that comes from panel conditioning as well as to identify its underlying mechanisms.

Panel conditioning effects describe learning effects that occur when the participation in prior waves of the same study affects respondents’ answers in subsequent interviews causing artificial changes which cannot be differentiated from real changes in respondents’ behavior, attitudes, and knowledge over time. This endangers the most important aims of longitudinal research, namely the valid measurement of stability and change.


The project’s major goal is to gain a deeper understanding of the magnitude (i.e., effect size) of PCE and the mechanisms that cause PCE in order to advance the theoretical and empirical knowledge about panel conditioning. PCE have received growing attention within the research, however, little is still known about their magnitude for different question types (i.e., knowledge, attitudes, and behavior) and dosage conditions (i.e., the frequency with which identical questions are asked across panel waves) as well as the significance of different theoretically proposed mechanisms that cause panel conditioning. The project’s findings will serve as a basis for future recommendations and best practice advice for researchers conducting and working with data of longitudinal studies. Accordingly, there are three main objectives:

  • to provide evidence for the relative significance of different mechanisms leading to PCE: changes in knowledge, attitudes, behaviors or changes in reporting of these characteristics due to reflection, satisficing and SD-bias.
  • to identify the magnitude (i.e., effect size) and significance of PCE for the different question types commonly used in social surveys (i.e., attitudes, behavior, and knowledge questions), and different dosage conditions, that is the different number of times identical questions are asked (conditioning frequency), and the different time intervals between survey waves (conditioning interval).
  • to give recommendations for correction methods that will function as best practice advice. These recommendations will help to decrease measurement inaccuracy for different question types in panel studies.

The project will also have a decisive impact on evidence-based practice because it will help large-scale longitudinal studies with substantial public policy implications to account for potential measurement errors.