Table 1 Summary of regression models predicting cooperation at 3 different levels of analysis.

Wealth productivity (W)

1.002 (1.606)

− 5.146* (2.370)

− 9.496*** (2.986)

0.169 (1.624)

Baseline inequality (B)

3.282* (1.606)

1.365 (2.370)

3.300 (3.712)

3.501** (1.624)

Round (R)

0.248*** (0.051)

0.367*** (0.032)

0.233*** (0.023)

Gini coefficient (G)

− 24.203 (13.320)

Alter endowment (A)

− 1.433*** (0.385)

W × B

7.260* (3.352)

13.098** (5.407)

W × R

0.399*** (0.072)

B × R

0.145* (0.072)

W × B × R

− 0.485*** (0.102)

W × G

68.169*** (14.722)

B × G

7.102 (18.223)

W × B × G

− 80.240** (24.745)

W × A

1.110* (0.446)

B × A

1.099* (0.446)

Intercept

42.299*** (1.391)

37.679*** (1.676)

39.375*** (2.259)

37.042*** (1.438)

Level 2 variance component

23.33

23.85

22.32

Level 3 variance component

72.06