Table 5.

Determinants of attrition

	Participant’s drop out in period t (0 = no; 1 = yes)
	Pooled data			Without punishment	With punishment
	(1)	(2)	(3)	(4)	(5)
Punishment available	0.056	0.362	0.107
	(0.598)	(0.612)	(0.611)
Period	−0.093*	−0.118**	−0.094*	−0.193***	−0.184**
	(0.051)	(0.053)	(0.053)	(0.066)	(0.077)
First period	2.484***	2.375***	2.554***
	(0.377)	(0.376)	(0.382)
Earnings		−0.002	0.011
		(0.143)	(0.143)
Group member(s) dropped out in previous period			1.896***	1.677***	2.024***
			(0.382)	(0.500)	(0.574)
Relative average contribution				0.002	−0.082
				(0.025)	(0.053)
Relative average punishment received					−0.105
					(0.086)
Relative average punishment given					−0.100
					(0.086)
Constant	−4.064***	−3.979***	−4.220***	−3.619***	−2.321*
	(0.317)	(0.318)	(0.328)	(0.353)	(1.191)
N	8334	8332	8332	3998	3907
AIC	893.56	875.23	860.27	454.61	303.68

Values reflect estimates from proportional hazards models fitted to binary events of participants staying (0) or dropping out (1) in a given round of the session, conditional on not having dropped out yet. ‘Punishment available’ is a dummy for the presence or absence of punishment; ‘Period’ is the period number; ‘First period’ is a dummy for the first period; ‘Earnings’ reflect participants’ total earnings relative to all other participants in the experiment in a given period; ‘Group member(s) dropped out in previous period’ is a dummy taking the value of 0 (1) when none (at least one) of the group members had left the session in the previous round (potentially delaying the progress within the session); ‘Relative average contribution’ is the participant’s average contribution to the public good minus the average contribution of their fellow group members in all rounds of the session so far; ‘Relative average received (given) punishment’ are the average punishment received (given) by a participant minus the average punishment received (given) by their fellow group members in all rounds so far

* p < 0.10; ** p < 0.05; *** p < 0.01