This Element introduces the testing of measurement invariance/DIF through nonlinear factor analysis and uses models to formulate different definitions of measurement invariance and DIF and different procedures for locating and quantifying these effects.
Measurement invariance and differential item functioning (DIF) are critical concepts in developmental psychology, as biased measurements can lead to incorrect conclusions about developmental phenomena. This Element explores the testing of measurement invariance and DIF through nonlinear factor analysis, presenting models and definitions relevant to these concepts. It also discusses various procedures for identifying and quantifying these biases. Additionally, it offers practical recommendations for researchers to ensure valid inferences in their data analysis.