In this model, is common to all items in level-1, as it is the location of the reference item to ψ0j identify the scale; thus it is the overall difference between males and females on all items the – difference in ability between male and female respondents. Final estimation of fixed effects: (Unit-specific model) Standard Approx. Fixed Effect Coefficient t-ratio p-value error d.f. For INTRCPT1, ψ0 INTRCPT2, 1.644895 0.043713 37.629 7638 <0.001 γ00 FEMALE, -0.181614 0.045773 -3.968 7638 <0.001 γ01 For IND1 slope, ψ1 INTRCPT2, 0.530804 0.047740 11.119 38002 <0.001 γ10 For IND2 ψ2 INTRCPT2, 0.281827 0.046271 6.091 38002 <0.001 γ20 For IND3 slope, ψ3 INTRCPT2, -0.082237 0.044585 -1.844 38002 0.065 γ30 For IND4 slope, ψ4 INTRCPT2, 1.056250 0.051822 20.382 38002 <0.001 γ40 For IND5 slope, ψ5 INTRCPT2, -0.477160 0.043183 -11.050 38002 <0.001 γ50 A Model for DIF Final estimation of fixed effects: (Unit-specific model) Standard Approx. Fixed Effect Coefficient t-ratio p-value error d.f. For INTRCPT1, ψ0 INTRCPT2, 1.652380 0.053370 30.961 7638 <0.001 γ00 FEMALE, -0.195052 0.073457 -2.655 7638 0.008 γ01 For IND1 slope, ψ1 INTRCPT2, 0.535299 0.069964 7.651 37997 <0.001 γ10
In this model, ψ0j is common to all items in level-1, as it is the location of the reference item to identify the scale; thus it is the overall difference between males and females on all items – the difference in ability between male and female respondents. Final estimation of fixed effects: (Unit-specific model) Fixed Effect Coefficient Standard error t-ratio Approx. d.f. p-value For INTRCPT1, ψ0 INTRCPT2, γ00 1.644895 0.043713 37.629 7638 <0.001 FEMALE, γ01 -0.181614 0.045773 -3.968 7638 <0.001 For IND1 slope, ψ1 INTRCPT2, γ10 0.530804 0.047740 11.119 38002 <0.001 For IND2 ψ2 INTRCPT2, γ20 0.281827 0.046271 6.091 38002 <0.001 For IND3 slope, ψ3 INTRCPT2, γ30 -0.082237 0.044585 -1.844 38002 0.065 For IND4 slope, ψ4 INTRCPT2, γ40 1.056250 0.051822 20.382 38002 <0.001 For IND5 slope, ψ5 INTRCPT2, γ50 -0.477160 0.043183 -11.050 38002 <0.001 A Model for DIF Final estimation of fixed effects: (Unit-specific model) Fixed Effect Coefficient Standard error t-ratio Approx. d.f. p-value For INTRCPT1, ψ0 INTRCPT2, γ00 1.652380 0.053370 30.961 7638 <0.001 FEMALE, γ01 -0.195052 0.073457 -2.655 7638 0.008 For IND1 slope, ψ1 INTRCPT2, γ10 0.535299 0.069964 7.651 37997 <0.001
Item-Response-Models.docx