Table 1 Control variables and pretest performance scores (means with standard deviations; minimum and maximum in parentheses)

15.39 ± 0.55 (15–17)

15.62 ± 0.74 (14–18)

15.57 ± 0.61 (15–17)

15.65 ± 0.66 (15–17)

15.58 ± 0.65 (14–18)

2.51 ± 0.73 (1–4)

2.61 ± 0.91 (1–5)

2.77 ± 0.75 (1–5)

2.77 ± 0.75 (1–5)

2.65 ± 0.85 (1–5)

13.05 ± 2.88 (8–20)

11.58 ± 3.34 (2–18)

12.90 ± 2.78 (7–17)

12.74 ± 2.77 (7–18)

12.52 ± 2.99 (2–20)

6.41 ± 2.61 (2–11)

5.86 ± 2.31 (0–12)

6.23 ± 2.31 (1–12)

5.90 ± 2.10 (2–10)

6.07 ± 2.30 (0–12)

10.08 ± 2.51 (3–15)

9.29 ± 2.92 (3–18)

9.93 ± 2.57 (3–17)

9.57 ± 2.78 (3–18)

9.68 ± 2.72 (3–18)

3.51 ± 1.68 (0–7)

3.45 ± 1.84 (0–10)

3.90 ± 1.87 (0–9)

3.84 ± 1.78 (1–9)

3.70 ± 1.81 (0–10)