Table 2.

Quality Assessment Matrix, Quantitative Studies [29]

Study	Howarth, Sommer & Jordan [31]	Liao, Taghinejadi & Creighton [32]	Zwier [30]
Question/objective sufficiently described?	Yes	Yes	Yes
Study design evident and appropriate?	Yes	Yes	Yes
Method of subject/comparison group selection described and appropriate?	Partial	Yes	Partial
Subject (and comparison group) characteristics sufficiently described?	Partial	Yes	Yes
Outcomes well defined and robust to measurement/misclassification bias? Means of assessment reported?	Yes	Yes	Yes
Sample size appropriate?	Partial	Yes	Yes
Analytic methods described/justified and appropriate?	Yes	Yes	Yes
Some estimate of variance is reported for the main results?	Yes	N/A	Yes
Controlled for confounding?	Partial	N/A	Yes
Results reported in sufficient detail?	Yes	Yes	Yes
Conclusions supported by the results?	Yes	Yes	Yes