Table 5.

Differential Item Functioning (DIF) Summary

Item name	Item description	IRT Wald Test			lordif results
		Age	Education	Interview language	Age	Education	Interview language
PSS1	In the last month, how often have you been upset because of something that happened unexpectedly?
PSS2	In the last month, how often have you felt that you were unable to control the important things in your life?
PSS3	In the last month, how often have you felt nervous and stressed?
PSS4R	In the last month, how often have you felt confident about your ability to handle your personal problems?		NU
PSS5R	In the last month, how often have you felt that things were going your way?						NU X
PSS6	In the last month, how often have you felt that you could not cope with all the things you had to do?
PSS7R	In the last month, how often have you been able to control irritations in your life?
PSS8R	In the last month, how often have you felt that you were on top of things?						U X NCDIF= 0.0621
PSS9	In the last month, how often have you been angered because of things that happened that were outside of your control?
PSS10	In the last month, how often have you felt difficulties were piling up so high that you could not overcome them?						U X

U = Uniform DIF; NU=Non-Uniform DIF; no items showed DIF after the Bonferroni correction

X = Identified using Chi-Square criterion (< 0.01)

NCDIF = Non-compensatory DIF index; NCDIF threshold for 5 response categories = 0.0960