Table 3.

Incremental evaluation of contributions of covariates to regression models of all comparisons (k=93), Random Effects (Restricted Maximum Likelihood), Knapp Hartung, Normalized Mean Difference

	Current Model			Test of Model (a)				Goodness of fit (b)			Change from prior(c,d)		Test of change (c)
Set	Covariate	Tau2	R2	F	df1	df2	P-value	Q	df	P-value	Tau2	R2	F	df1	df2	P-value
	Intercept	213	0
	Study Quality	175	0.18	13	1	91	0.0005	296	91	<0.0001	-38	0.18	13	1	91	0.0005
	Timing of Treatment	174	0.18	7	2	90	0.0019	289	90	<0.0001	-0.8	0	0.6	1	90	0.4568
Duration of Ischemia*	60	178	0.16	4	3	89	0.0060	281	89	<0.0001	4	0	0.0	1	89	0.8494
	90	179	0.16	3	4	88	0.0122	279	88	<0.0001	0.6	0	0.4	1	88	0.5380
	120	182	0.14	3	5	87	0.0244	278	87	<0.0001	3	0	0.2	1	87	0.6791

This is a tabulation of statistics from a series of separate models. The first row is a model with no covariates, the second row has one covariate, and so on. The results evaluate the impact of each covariate when prior covariates in the model are held constant. (a) Simultaneous test that all coefficients up to and including the current row are zero. (b) Test that all with covariates up to and including the current row in the model, the residual is zero. (c) Change from the prior row to the current due to the added covariate. (d) The row-to-row increase in Tau² and decrease in R² reflects sampling error. The reference groups for timing of intervention and duration of ischemia were treatment during/afer ischemia and permanent ischemia respectively. *When considered as a set, transient ischemia was not a significant covariate in the model (F=0.19, df1=3, df2=87, p=0.8996). Table format adapted from Comprehensive Meta-analysis®. * - minutes. Abbreviations: df – degrees of freedom, k – number of comparisons between treatment and control; Timing of Treatment: before vs during/after ischemia.