Why does peer instruction benefit student learning?

Cognitive Research: Principles and Implications

Table 4 The gamma correlation between accuracy and confidence before and after discussion for each class

Class	Pre-gamma	Post-gamma	SD of difference	Paired t test comparing pre to post^a	Cohen’s d
Cognitive Psych (Psych) 2015	0.60	0.79	0.52	t (18) = 1.22, p = 0.24	0.29
Cognitive Psych (Psych) 2017	0.27	0.40	0.74	t (37) = 2.29, p = 0.02	0.38
Decision Making (Ed Psych) 2016	0.36	0.56	0.46	t (22) = 3.21, p = 0.004	0.47
Decision Making (Ed Psych) 2017	0.47	0.44	0.46	t (33) = 0.24, p = 0.81	− 0.04
Learning Theories (Ed Psych) 2016	0.18	0.28	0.45	t (11) = 1.57, p = 0.14	0.23
Learning Theories (Ed Psych) 2018	0.43	0.37	0.37	t (13) = 0.58, p = 0.57	− 0.16
Overall	0.40	0.48	0.55	t (139) = 2.98, p = 0.003	0.24

^aGamma correlation requires that learners have variance in both confidence and correctness before and after discussion. Degrees of freedom are reduced because many students did not have requisite variation