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Table 3 CTT statistical measures desired values

From: Evaluating the quality of the ontology-based auto-generated questions

CTT statistical measures Desired values Literature
Difficulty index average [0.30-0.90] (Doran 1980; Ding et al. 2006)
Discrimination index average ≥0.30 (Doran 1980; Zhang and Lidbury 2013)
Point biserial coefficient average ≥0.20 (Ding and Beichner 2009; Zhang and Lidbury 2013; Kline 1986; Ding et al. 2006)
Cronbach’s α ≥0.70 (Doran 1980; Kline 2013a)
Fergusons δ ≥0.90 (Kline 1986; 2013a; 2013b)