Validation studies show no significant differences in IDI results based on gender or age.
Rigorous Differential Item Function (DIF) analysis (a method to evaluate whether different subgroups respond differently to particular items within a scale) found IDI results do not favor any particular group. In the DIF analysis, the performance of respondents on each item were reviewed to evaluate if the item appeared to unfairly favor one group over another (e.g., cultural bias) in the items on the IDI.
See more information in the 2016-2017 IDI Validation Results.