Results
Item difficulties of EORTC QLQ-C30 The most difficult item was question 5 (Do you need help
with eating, dressing, washing yourself or using the toilet?),as shown in Table 1. The easiest question was 18 (Were you tired?). Expected response scores, as anticipated, presented an acceptable infit MNSQ more often than observed scores, which displayed two items outside
of the range 0.5-1.5. From the observed score perspective,question 5 had an infit MNSQ of 1.6, and question 28 had an infit MNSQ of 1.74, indicating some aberrant responses on those two questions that negatively affected the inferences and conclusions that were made.