Table 2. Results of the statistical analyses (ANOVAs) of the effect of photostimulation on first egg laying dates (date at which the first egg of a clutch is laid) of wild great tits (Parus major) in the field experiment.

Subset	Variable	df	Error df	Sum of squares	Mean squares	F	P
Oosterhout	Treatment * year	2	33	1.05	0.53	0.05	0.96
Oosterhout	Treatment	2	36	38.39	19.19	1.59	0.22
2009	Treatment * location	2	30	40.35	20.18	0.96	0.39
2009	Treatment	2	33	3.02	1.51	0.06	0.94

The experiment had three treatments: indoor photostimulated; indoor natural light regime; not taken indoors. The experiment was done in two locations in 2009 and in one location in 2010. We divided the analyses in two; i) only data from the Oosterhout population (2009 and 2010) and ii) only data from 2009, where the experiment was done in Oosterhout and Hoge Veluwe population.