Are you currently combining or planning to combine data from different survey programs? Or are you involved in a survey which plans to change a question (e.g., in a time series)?
Then you are probably aware of a central methodological challenge: How can data measured with different instruments be made comparable? Or in other words: How can responses collected with different instruments be transformed so that they form a seamlessly harmonized variable?
To support you in this, GESIS offers information and consulting on the harmonization of substantive variables measured with different instruments.
A special focus of methodological research and consulting in this area is the harmonization of instruments which capture latent constructs, such as values, attitudes, intentions, interests, emotions, or personality traits. Unlike manifest constructs, intangible constructs have no natural units. We can measure income in currency units and behavior in times per month. But how much political interest is “very interested”; and how does that compare to “very strongly”? In short, we want to compare apples and oranges.
Equating is a very promising approach to overcome that challenge. Equating originates from psychometric performance and aptitude diagnostics, where it is used to make results from different tests comparable. Despite equating’s psychometric roots, it can also be applied to instruments with only one question with observed score equating. The advantages of equating lie in its solid mathematical and empirical foundation and its usefulness as a general framework to evaluate the quality of instrument harmonization. However, in addition to equating, other approaches are available on which we consult you as well.
- Assessing the comparability of different instruments
- Weighing the potential consequences of a lack of comparability
- Harmonizing substantive variables measured with different instruments; especially latent constructs
Our advice as help for self-help is free of charge. For extensive, project-specific advice on the ex-post harmonisation of survey instruments and data, we charge an expense allowance of 80 euros per hour.
QuestionLink is a database of recoding scripts. For selected constructs the scripts harmonize all German instruments that were used by nine national or international survey programs.
- GESIS Blog-Reihe: Adventures in Ex-post Harmonization: Blogposts mit kurzweiligen Einführen in viele Aspekte der ex-post Harmonisierung.
- Meet the Experts: Effiziente Harmonisierung von Umfrageskalen: Ein kurzer Überblick über methodische Herausforderungen und Lösungsansätze.
- NFDI Science Slam “The Sum and Its Parts: The benefits of combining data from different surveys”: Warum sollten überhaupt wir Daten verschiedener Umfrageprogramme zusammenlegen und gemeinsam analysieren?
- Singh, Ranjit K.. 2020. Harmonizing instruments with equating. Harmonization Newsletter on Survey Data Harmonization in the Social Sciences 6, 1. Warschau: Cross-national Studies: Interdisciplinary Research and Training Program. urn: urn:nbn:de:0168-ssoar-68262-1 .
- Roth, Matthias, and Ranjit K. Singh. 2021. "Harmonizing frequency and quantity questions using equating." 9th Conference of the European Research Association (ESRA), online, 23.07.2021. https://www.europeansurveyresearch.org/conferences/program2021?sess=3#14.