Table 3.

Meta-regression analysis for latitude, daylight and age of study.

	Latitude Coefficient (95%CI)	p-value	Variance accounted	Daylight Coefficient (95%CI)	p-value	Variance accounted	Age of Study Coefficient (95%CI)	p-value	Variance accounted (%)
January	0.0004 (−0.0014 to 0.0023)	0.65	0%	−0.0002 (−0.0007 to 0.0004)	0.52	0%	−0.0004 [-0.0023 to 0.0016]	0.19	0
February	−0.0007 (−0.0018 to 0.0005)	0.28	41%	0.00 (−0.0004 to 0.0005)	0.38	0%	0.0006 [-0.0009 to 0.0020]	0.84	0
March	0.00 (−0.0023 to 0.0024)	0.97	0%	0.0005 (−0.0003 to 0.0013)	0.49	4%	0.0006 [-0.0018 to 0.0030]	0.87	0
April	0.0011 (−0.0002 to 0.0025)	0.10	0%	0.0003 (−0.0003 to 0.0009)	0.46	7%	0.0015 [0.0004 to 0.0026]	0.006	92
May	−0.0003 (−0.0015 to 0.0009)	0.60	0%	−0.0001 (−0.0005 to 0.0003)	0.58	0%	0.0010 [0.00 to 0.0021]	0.05	96
June	0.0005 (−0.0015 to 0.0025)	0.60	0%	0.0003 (−0.0002 to 0.0009)	0.18	3%	0.0003 [-0.0018 to 0.0024]	0.75	0
July	0.0004 (−0.0012 to 0.0019)	0.65	0%	0.0001 (−0.0004 to 0.0005)	0.68	0%	0.0005 [-0.0011 to 0.0021]	0.54	0
August	0.00 (−0.0018 to 0.0018)	0.90	0%	0.0004 (−0.0003 to 0.0011)	0.09	2%	0.0018 [0.00 to 0.0035]	0.05	18
September	0.0002 (−0.0015 to 0.0020)	0.80	0%	−0.0005 (−0.0011 to 0.0001)	0.13	16%	−0.0012 [-0.0029 to 0.0005]	0.15	21
October	−0.0003 (−0.0013 to 0.0007)	0.53	0%	0.00 (−0.0004 to 0.0003)	0.78	0%	−0.0006 [-0.0016 to 0.0004]	0.26	0
November	0.0013 (−0.0007 to 0.0033)	0.70	0%	−0.0002 (−0.0007 to 0.0003)	0.36	14%	−0.002 [-0.0031 to −0.001]	<0.001	100
December	−0.0013 (−0.0045 to 0.0019)	0.43	0%	0.0006 (−0.0005 to 0.0016)	0.28	0%	−0.0030 [-0.006 to 0.0001]	0.06	15