The second step in developing commensurate measures is item selection. This includes a review of all individual items assessing a target construct, with the goal of identifying a core set of items that define a unidimensional factor. This core set of items will include both common and unique items. This step involves the use of content experts to identify and narrow the potential item pool, descriptive statistics to identify potentially problematic items, and exploratory factor analyses to evaluate dimensionality. One goal of this step is to identify an item pool that maximizes the number of common items which are core to the construct of interest and provide opportunities to link measurement across studies.
