Appendix B, Figure 1
Easy Items

r value
Lower 1/3
All
Easy Items
0.16
0.84
0.93

Appendix B, Figure 2
Moderately Difficult Items

r value
Lower 1/3
All
Moderately Difficult Items
0.41
0.59
0.78

Appendix B, Figure 3
Difficult Items

r value
Lower 1/3
All
Difficult Items
0.63
0.37
0.64