Skip to main content

Table 3 Mean values, item fit statistics and PSI values for three item sets among students in grades 5, 7 and 9. Randomly sampled group sizes of 3500

From: Explaining differential item functioning focusing on the crucial role of external information – an example from the measurement of adolescent mental health

  Item Set 1 Original 8 items Item Set 2 Resolving Felt low for boys; girls no period; girls period Item Set 3 Resolving Felt low and Stomach ache for boys; girls no period; girls period Difference in difference Set 2 and 3 Difference in difference Set 1 and 2 Difference in difference Set 1 and 3
Boys 1.088 1.065 1.042    
Girls no period 0.951 0.956 0.985    
Girls period 0.005 0.056 0.114    
Difference Boys-Girls no period 0.137 0.109 0.057 0.052 0.028 0.080
Difference Girls no period-Girls period 0.946 0.900 0.871 0.029 0.046 0.075
Person Separation Index 0.76195 0.75846 0.75501    
Overall item fit Chi Square Probability (adjusted sample size of 1500) 0.005361 0.182495 0.532964