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Table 2 Item difficulty and discrimination for the knowledge index

From: Development of the Informed Choice in Mammography Screening Questionnaire (IMQ): factor structure, reliability, and validity

Item Item 7 item model   6 item model*  
No.   Item discrimination (SE) Item difficulty (SE) Item discrimination (SE) Item difficulty (SE)
K1 When to participate in the MSP (No breast complaints/ Breast complaints/ In both cases) 0.267 (0.036) 4.040 (0.520) 0.256 (0.036) 4.202 (0.560)
K2 Number of women receiving a positive result (1-20 of 200/ 21-50 of 200/ 51-100 of 200/ 101-200 of 200) 0.428 (0.038) 2.411 (0.192) 0.403 (0.037) 2.537 (0.212)
K3 Positive MSP result means breast cancer (Yes/ No) 0.810 (0.060) -0.782 (0.046) 0.805 (0.061) -0.785 (0.047)
K4 MSP discovers every breast cancer (Yes/ No) 0.710 (0.049) -0.126 (0.030) 0.812 (0.062) -0.115 (0.028)
K5 More likely to get the diagnosis breast cancer (Women participating in the MSP/ Women not participating in the MSP/ Both the same) 0.202 (0.031) 4.442 (0.671) 0.120 (0.030) 7.341 (1.836)
K6 More likely to die of breast cancer (Women participating in the MSP/ Women not participating in the MSP/ Both the same) 0.208 (0.028) -1.505 (0.209) - -
K7 Existence of overtreatment (Yes/ No) 0.450 (0.033) 0.623 (0.057) 0.433 (0.033) 0.644 (0.060)
  1. Note. Correct answers in italics. * Item 6 was excluded