When applying statistical procedures to assess for DIF, the "a" and "b" parameters (discrimination and difficulty) are of particular interest. However, assume a 1PL model was used, where the "a" parameters are constrained to be equal for both groups leaving only the estimation of the "b" parameters. After examining the ICCs, there is an apparent difference in "b" parameters for both groups. Using a similar method to a Student's t-test, the next step is to determine if the difference in difficulty is statistically significant. Under the null hypothesis