Analysis method
Factorial model
Estimation of declared factor effects and interactions.
Input
Trial-level ratings, ranks, or choices; factor assignments; and participant identifiers.
Model
Fit item effects, declared factor effects, and specified interactions in one hierarchical model. Include participant-level variation.
Results
Report effect estimates, interaction estimates, intervals, model specification, and design terms that cannot be identified.
Validity
Factor definitions, contrasts, interactions, exclusions, and the reduced design must be declared before data collection.