Although the results of individual studies are always questionable, a range of peer reviewed studies on the effects of small classes have now emerged, and they throw into doubt this advice. (educationmattersmag.com.au)
Further, the definition of adaptation is variable in individual studies with a number of predictor variables often defined as outcomes of adaptation and vice versa. (link.springer.com)
Results from individual studies were combined and number needed to treat and relative risk of response (primary outcome) were calculated using a random effects model. (ebmh.bmj.com)