Rozeboom, William W.2011-06-102011-06-101989Rozeboom, William W. (1989). The reliability of a linear composite of nonequivalent subtests. Applied Psychological Measurement, 13, 277-283. doi:10.1177/014662168901300307doi:10.1177/014662168901300307https://hdl.handle.net/11299/107320Traditional formulas for estimating the reliability of a composite test from its internal item statistics are inappropriate to judge the reliability of multiple regressions and other weighted composites of subtests that are appreciably nonequivalent. Formulas are provided here for the reliability of such a composite given the reliabilities of its component subtests, followed by a comparison of the composite’s reliability to that of its components. Compositing can easily incur a substantial loss of reliability, though gains are entirely possible as well. Index terms: combining nonequivalent subtests, composite reliability, item weighting, nonequivalent subtests, nonhomogeneous item composites.enArticle