Table 2.

Questions answered according to types of synthesis methods and types of data used

Question answered	Synthesis method	Minimum data required
		Estimate of effect	Variance	Direction of effect	Precise P value
What is the common intervention effect? What is the average intervention effect? Which intervention, of multiple, is most effective? What factors modify the magnitude of the intervention effects?	Meta-analysis of effect estimates and extensions (eg, sub-group analysis, meta-regression, network meta-analysis)	✔	✔	-	-
What is the range and distribution of observed effects?	Summarising effect estimates	✔	-	-	-
Is there evidence of an effect in at least one study?	Combining P values	-	-	✔	✔
Is there any evidence of an effect?	Vote counting based on direction of effect	-	-	✔	-

Abbreviated from table 12.2.a of McKenzie and Brennan 2019.¹¹