Partial Credit Analysis of Writing Ability

Abstract

The direct assessment of the writing ability of 2000 randomly selected secondary school students was performed using the partial credit model. The effects on item parameter estimates of rating scale and type of writing sample were investigated. The rating scales used were a sum and an averaging of the individual raters' ratings and the types of items were expository and narrative. Results showed that expository items tended to provide more information for high ability examinees than did narrative items and that the sum holistic rating method yielded greater information than did the average holistic rating scale. Additional analyses of the rating scales used as well as implications for test construction are discussed.