The Rasch model is used to model the relation between individual location (ability) on a latent trait and their probability of endorsing a dichotomous item, which is characterized by its difficulty, assuming all items are equally discriminative.

The Rasch measurement model is the simplest of the item response theory (IRT) family of measurement models. Due to the simplicity of the model, it allows smaller sample sizes to arrive at stable parameter estimates. The Rasch model will analyze data that are: 1) dichotomous (right or wrong), 2) polytomous (rating scale or partial credit items, and 3) many-faceted (e.g., raters, items, and students).