Retrospective harmonisation of data obtained through different instruments creates measurement error, even if the underlying concepts are assumed the same.
We tested a novel method for item-level data harmonisation of two widely used instruments that measure emotional and behavioural problems: the Child Behavior Checklist (CBCL) and the Strengths and Difficulties Questionnaire (SDQ). We found he harmonised dimensions of emotional, peer relationship, hyperactivity/inattention and conduct problems are invariant across the CBCL and SDQ suggesting that these dimensions can be reliably compared with limited measurement error.
Baumann, N., Anderson, P. J., Johnson, S., Marlow, N., Wolke, D., & Jaekel, J. (2024). Harmonisation of assessments of attention, social, emotional, and behaviour problems using the Child Behavior Checklist and the Strengths and Difficulties Questionnaire. International Journal of Methods in Psychiatric Research, 33(1). https://doi.org/10.1002/mpr.2001