Importantly, the method allows for the detection of item bias independent of true differences in limitation between the groups.
2. What factors influence correct (true positive) and incorrect (false positive) detection of item-level mode DIF using each procedure?
Rasch analysis allows a detailed investigation of many aspects of a scale including the response format, the fit of individual items and persons, dimensionality, targeting, and the detection of item bias.
After this step the database included 346 items To facilitate the detection of redundant items in this large item set, all items were first classified into ad-hoc categories (e.g. physical, social, household, energy) that were set up by the reviewers.
In the three-way ANOVA across both versions, we observed a main effect of "item type", indicating that detection of new items was better than recognition of old items; in the short version, the rate of correct rejections was not significantly affected by group opinion as long as at least one out of four confederates gave a correct responses.
These results suggest that previous findings that social conformity affects detection of new items stronger than recognition of old items [19] cannot be easily generalized to real-world conditions.
To enable the detection of significant items even when not present in all datasets, missing items from at most one dataset were included, dragging a P-value penalty equals to one instead of a missing value.
We apply our algorithm to the detection of frequent items in both real and synthetic datasets whose probability distribution functions are a Hurwitz and a Zipf distribution respectively.
