Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Begg's funnel plot for assessing the presence of publication bias. Weighted mean difference was plotted against the precision of the study (p = 0.03, for Begg's adjusted rank correlation test and p = 0.06, for Egger's regression asymmetry test).
