In some situations where reliability must be estimated it is impossible to divide the measuring instrument into more than two separately scoreable parts. In such a case, neither Cronbach's coefficient alpha nor Kristof's three-part approach are satisfactory. A technique is developed for estimating reliability in such situations. (Author/BJG)

Presently available test statistics for the Rasch model are shown to be insensitive to violations of the assumption of test unidimensionality. Two new statistics are presented. One is similar to available statistics, but with some improvements; the other addresses the problem of insensitivity to unidimensionality. (Author/JKS)

A procedure is developed for estimating correlations among new tests when non-overlapping sub-samples each are administered a different new test and all sub-samples are administered a set of standard tests. (JKS)