Empirically indistinguishable multidimensional IRT and locally dependent unidimensional item response models

Area of Science:

• Psychometrics
• Psychological Measurement
• Personality Assessment

Background:

• Psychological constructs are often theoretically unidimensional, but real-world data exhibit multidimensionality.
• Previous research focused on simulated data to test unidimensional models with multidimensional data.
• A gap exists in theoretical investigations of model identifiability with multidimensional data.

Purpose of the Study:

• To theoretically investigate the empirical distinguishability between multidimensional and unidimensional item response models.
• To explore the implications for psychological data analysis when multidimensionality is present.
• To discuss the utility of locally dependent unidimensional models as an alternative.

Main Methods:

• Theoretical investigation of item response models.
• Analysis of model identifiability under multidimensional data conditions.
• Conceptual exploration of alternative modeling approaches.

Main Results:

• A multidimensional item response model is empirically indistinguishable from a locally dependent unidimensional model.
• The single dimension in the unidimensional model represents the primary construct of interest.
• Multidimensional data does not inherently necessitate multidimensional modeling.

Conclusions:

• The use of multidimensional models is not always required for multidimensional response data.
• Locally dependent unidimensional models offer a viable alternative in certain psychological measurement contexts.
• Further discussion is needed on the specific circumstances favoring unidimensional approaches.