Table 3.

Between-level comparisons in test result improvements

Level comparisons	Results	p	Cohen's d
Group 1 (eCases)
Level 1 vs. level 2	66% vs. 70%	0.03	0.86
Level 2 vs. level 2+	70% vs. 71%	0.73	0.07
Group 2 (eTextbook)
Level 1 vs. level 2	43% vs. 48%	0.002	0.94
Level 2 vs. level 2+	48% vs. 49%	0.81	0.12

Mann–Whitney U test for all comparisons. N=20 in each group. Cohen's effect size value (d): high (>0.8), moderate (0.5–0.8), or small (0.2–0.5) practical significance.