. Author manuscript; available in PMC: 2015 Dec 1.

Published in final edited form as: Hum Nat. 2014 Dec;25(4):538–566. doi: 10.1007/s12110-014-9213-4

Table 3.

Group performance with and without elected leaders

Community	Task	No. of Groups	Avg. completion time (min) w/o elected leader	Avg. completion time (min) w/elected leader	% Faster w/elected leader	One-tailed p^a

Ton'tumsi	Web	6	16.96	11.61	32
	River	6	13.66	10.70	22
	Both	12	15.31	11.15	27	0.06

Virje	Web	4	33.21	57.92	–74
	River	4	34.68	17.69	49

Both	8	33.95	37.80	–11	0.50
Both	Both	20	22.76	21.81	4	0.11

significance estimated by Wilcoxon signed-rank tests