To investigate the effect on item parameter estimation of pooling the raters' ratings and to examine the information content of 2 types of writing samples, the partial credit model was fit to 2,000 writing samples from secondary students that had been holistically scored. Implications for test construction are discussed. (SLD)

The graded response (GR) model of Samejima (1969) and the partial credit model (PC) of Masters (1982) were fitted to identical writing samples that were holistically scored. The performance and relative benefits of each model were then evaluated. Writing samples were both expository and narrative. Data were from statewide assessments of secondary…