Development of an abbreviated Personal Globe Inventory using item response theory: The PGI-Short

The responses of 2813 individuals to the Personal Globe Inventory (Tracey, 2002) were examined with the goal of developing a shorter, yet valid version of the scale using item response theory to guide the process. A random sample of 1000 individuals was used to select the best items and then the remaining 1813 were used as a validation sample to examine psychometric properties. For items to be included in the shortened form, the option characteristic curves had to conform to theory and there could be no presence of differential item functioning across either gender or ethnicity. The best 80 items were retained forming the PGI-Short. This instrument demonstrated excellent reliability and adherence to a circular model, there was no differential item functioning across either gender or ethnicity. The PGI-Short was supported as an alternative to the fuller version of the PGI.