Scoring neuropsychological tests using the Rasch model: an illustrative example with the Rey-Osterrieth Complex Figure.

Parametric statistical methods are typically used for analyzing test scores, even though they are ordinal at best. The Meyers and Meyers' Rey-Osterrieth Complex Figure four-category scoring system has been evaluated with the Rasch Rating Scale Model, and disordered thresholds have been found. However, Rasch-modeling dichotomized data led to good fit for both normal (n = 219) and Traumatic Brain Injury (n = 54) samples and generalized validity for these groups, as well as for male and female groups. The logarithmic transformation of the item and person data performed by the model converts the ordinal data to yield interval scaled data. This is desirable not only from a scientific perspective, but also from the point of view of interpretability and communicability.