Developing a unidimensional instrument to measure the effectiveness of school-based partnerships.

The purpose of this study was to refine an instrument designed to measure a single construct, the effectiveness of school-based partnerships. The instrument was designed to measure the "health" of the partnership teams and to identify specific problems for which intervention might be appropriate. The items were based on four theoretical models of partnering efforts. The partnerships studied were created to enhance the teaching of elementary school science and involved elementary teachers and resource professionals in school-based programs over a six-year period. The results show how Rasch analysis, using the item and person fit statistics, bias analysis using separate calibration groups for contrasts of interest, and principal component analysis can be used to evaluate the unidimensionality of a scale.