Editing Meta-analysis (section)

===Weak inclusion standards lead to misleading conclusions===

Meta-analyses in education are often not restrictive enough in regards to the methodological quality of the studies they include. For example, studies that include small samples or researcher-made measures lead to inflated effect size estimates.<ref>{{Cite journal| vauthors = Cheung AC, Slavin RE |date=2016-06-01|title=How Methodological Features Affect Effect Sizes in Education |journal=Educational Researcher|language=en|volume=45|issue=5|pages=283–292|doi=10.3102/0013189X16656615|s2cid=148531062|issn=0013-189X}}</ref> However, this problem also troubles meta-analysis of clinical trials. The use of different quality assessment tools (QATs) lead to including different studies and obtaining conflicting estimates of average treatment effects.<ref>{{cite journal | vauthors = Jüni P, Witschi A, Bloch R, Egger M | title = The hazards of scoring the quality of clinical trials for meta-analysis | journal = JAMA | volume = 282 | issue = 11 | pages = 1054–1060 | date = September 1999 | pmid = 10493204 | doi = 10.1001/jama.282.11.1054 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Armijo-Olivo S, Fuentes J, Ospina M, Saltaji H, Hartling L | title = Inconsistency in the items included in tools used in general health research and physical therapy to evaluate the methodological quality of randomized controlled trials: a descriptive analysis | journal = BMC Medical Research Methodology | volume = 13 | issue = 1 | pages = 116 | date = September 2013 | pmid = 24044807 | pmc = 3848693 | doi = 10.1186/1471-2288-13-116 | doi-access = free }}</ref>