Divgi, D. R.2011-06-172011-06-171985Divgi, D. R. (1985). A minimum chi-square method for developing a common metric in item response theory. Applied Psychological Measurement, 9, 413-415. doi:10.1177/014662168500900410doi:10.1177/014662168500900410https://hdl.handle.net/11299/107573The θ scale in item response theory has arbitrary unit and origin. When a group of items is calibrated twice, estimates from one calibration must be transformed to the metric of the other. A new method is presented for doing so. It is simpler than an earlier method based on test characteristic curves, and makes more complete use of available information.enArticle