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Differences in Item Functionality on the Perceived Stress Scale: An Application of Model-Based Recursive Partitioning Methods (308517)

Keywords: Perceived Stress Scale, Model-based Recursive Partitioning, Differential Item Functioning, Item Response Theory

When an item on a scale functions differently for subgroups of respondents with respect to an exogenous variable after conditioning on the latent variable of interest, the item is said to exhibit Differential Item Functioning (DIF). The 10-item Perceived Stress Scale is administered to respondents via MTurk to quantify “perceived stress” and identify if items on the scale function differently for specific subgroups. We consider traditional DIF techniques as the methods that require subgroups to be pre-specified, these include both item response theory (IRT) based methods and non IRT based methods. In this paper, we also consider Rasch Trees, a relatively new model-based recursive portioning approach developed by Strobl et al. With this method, subgroups do not need to be pre-specified and as a result, DIF can be detected in combinations of exogenous variables. Current results corroborate that while traditional methods detected DIF in specified groups, the Rasch tree approach detected DIF in subgroups that might not otherwise have been tested.