Table 2.

Degree of difficulty and discrimination index of the questions (Study 1).

		Degree of difficulty (correct answer rate)
		Hard (0%–50%)	Moderate (50%–85%)	Easy (85%–100%)
Discrimination index	Good (>0.3)	Q11, Q16, Q30, Q31, Q32, Q36, Q40, Q42, Q43, Q45, Q48, Q62, Q63, Q67, Q72, Q76, Q77	Q8, Q10, Q12, Q15, Q20, Q27, Q35, Q34, Q38, Q39, Q46, Q47, Q52, Q54, Q55, Q56, Q60, Q71, Q79	Q7, Q28, Q44, Q64, Q66
	Fair (0.1–0.3)	Q41, Q53, Q57, Q75	Q13, Q14, Q49, Q51, Q65, Q68, Q70
	Poor (<0.1)	Q17, Q22, Q23, Q26, Q50, Q69, Q80	Q6, Q9, Q24, Q25, Q29, Q33, Q61, Q74	Q2, Q4, Q21
	Undecidable			Q1, Q3, Q5, Q18, Q19, Q37, Q58, Q59, Q73, Q78

The degree of difficulty is the percentage of test takers who answered the question correctly. Here, the correct answer rate of 85% or more is defined as easy, 50%–85% is defined as moderate, and less than 50% is defined as difficult. The discrimination index is an index that distinguishes between those with high scores and those with low scores. The fourfold point correlation coefficient (φ coefficient) is calculated from the answer results of the top 25% and the bottom 25%. Here, a φ coefficient of less than 0.1 is defined as poor, 0.1–0.3 is defined as fair, and 0.3 or more is defined as good.