Table 5 Principal component analysis of the residuals and comparisons with simulated data

Total raw variance in observations

100%

100%

100%

Raw variance explained by Rasch model

37.2%

38.8%

38.4%

Raw variance explained by persons

16.1%

17.4%

16.8%

Raw variance explained by items

21.1%

21.3%

21.5%

Raw unexplained variance (total)

62.8%

61.2%

61.6%

Unexplained variance in first contrast in Eigenvalue, (%)

2.077 (7.2%)

1.67 (5.7%)

1.69 (5.8%)