A total of 57 publications (M study year = 1997, range = 1972–2007) with 98 separate com- parisons were included in our meta-analysis (a list of excluded studies is available from the first author).
A total of 57 publications (M study year =1997, range = 1972–2007) with 98 separate com- parisons were included in our meta-analysis (a list of excluded studies is available from the first author).