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The computer program LDIP provides indices of local dependence for polytomous items under item response theory (cf. Chen, 1998). The indices are the Pearson chi-square statistic χ 2 (Agresti, 1996), the likelihood ratio chi-square statistic G 2 (Agresti, 1996), Yen's (1993) index of local dependence Q 3 , and the Fisher-transformed correlation difference statistic Z d (Press, Flannery, Teukolsky, & Vetterling, 1986).LDIP is used in conjunction with the two popular item response theory computer programs for polytomous items, MULTILOG (Thissen, Chen, & Bock, 2002) and PARSCALE (Muraki & Bock, 2002). LDIP obtains the indices of local dependence for the graded response model (Samejima, 1969) and the generalized partial credit model (Muraki, 1992) using two result files that contain item parameter estimates and ability estimates from either MULTILOG or PARSCALE.The program is written in Fortran and compiled with Microsoft Fortran PowerStation. LDIP can be executed in a command prompt under Microsoft Windows XP or by clicking the LDIP icon. The program basically runs in an interactive mode with the user answering a series of questions and providing the necessary information. It is also possible to point LDIP to a batch input file using the redirect facility of the command prompt.

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