Table 1 Criteria for study quality review

LEVEL I – Randomized control trial (RCT) or experimental study

LEVEL II – Quasi-experimental (no manipulation of independent variable, may have random assignment or control)

LEVEL III – Non-experimental (no manipulation of independent variable, includes descriptive, comparative, correlational studies or uses secondary data)

LEVEL IV – Qualitative (focus groups, starting point where no previous data exists).

X – Study did not meet final inclusion criteria

A - HIGH

Consistent, generalizable results

Sufficient sample size

Adequate control

Definitive conclusions

Consistent recommendations based on comprehensive literature review that includes thorough reference to scientific evidence

B - GOOD

Reasonably consistent results

Sufficient sample size for the study design

Some control

Fairly definitive conclusions

Reasonably consistent recommendations based on fairly comprehensive literature review that includes some reference to scientific evidence

C - LOW

Little evidence with inconsistent results

Insufficient sample size for the study design

Conclusions cannot be drawn