Table 1. Descriptive statistics for all three projects.

			Stardust @home		CWOP		BOINC
Construct	Item	Range	Mean	STD	Mean	STD	Mean	STD
Collective Motives	Col1	[1..7]	6.43	0.87	6.09	0.93	6.21	1.09
	Col2	[1..7]	6.45	0.76	6.13	0.85	6.30	1.02
Norm-Oriented Motives	Nov1	[1..7]	4.78	1.34	5.10	1.20	4.20	1.41
	Nov2	[1..7]	4.87	1.11	4.76	1.15	4.08	1.35
	Nov3	[1..7]	4.75	1.32	4.65	1.14	3.87	1.43
Reputation	Rep1	[1..7]	3.62	1.47	4.11	1.48	2.68	1.62
	Rep2	[1..7]	3.64	1.56	3.73	1.44	2.97	1.72
	Rep3	[1..7]	4.20	1.57	4.47	1.37	3.38	1.76
Intrinsic Motives	Int1	[1..7]	6.00	0.84	5.76	1.06	5.18	1.42
	Int2	[1..7]	6.38	0.62	6.05	0.84	5.89	1.13
Age	Age1		46.32	15.26	52.30	15.56	42.56	14.09
Gender	Gen1	0/1	0.78	0.42	0.97	0.17	0.94	0.24
Expertise	Exp1	[1..7]	5.36	1.11	5.87	0.98	5.56	1.23
Quantity of Contributions	Qnt1	[1..7]	5.33	1.34	4.77	1.24	4.48	1.61
	Qnt2	[1..7]	5.42	1.35	4.63	1.23	4.82	1.61
Quality of Contributions	Qual1	[0..1]	0.67	0.30