Linking Unlinkable Tests: A Step Forward

Random Equating (RE) and Heuristic Approach (HA) are two linking procedures that may be used to compare the scores of individuals in two tests that measure the same latent trait, in conditions where there are no common items or individuals. In this study, RE—that may only be used when the individuals taking the two tests come from the same population—was used as a benchmark for evaluating HA, which, in contrast, does not require any distributional assumptions. The comparison was based on both simulated and empirical data. Simulations showed that HA was good at reproducing the link shift connecting the difficulty parameters of the two sets of items, performing similarly to RE under the condition of slight violation of the distributional assumption. Empirical results showed satisfactory correspondence between the estimates of item and person parameters obtained via the two procedures.