One was a qualitative study and seven were quantitative studies, of which four were randomized cotrolled trials, two quasi-experimental studies and one analytical cross sectional study.
Af þeim var ein rannsókn eigindleg og sjö megindlegar. Af þeim voru fjórar slembnar samanburðar rannsóknir, tvær hálfstaðlaðar og ein þverrannsókn.