Comparison of Sample Populations
Half of the studies evaluated for this study were reviews of other studies done in the past either in the form of systematic literature reviews or meta-analyses. Sahoo et al. (2015) evaluated literature reviews but does not mention the methodological process; hence, the sample size is not clear. Similarly, Xu and Xue (2016) has a random evaluation of literature with no review of the methodology; hence, the exact sample is unknown. Ayer et al. (2015) sample is made up of primary cohort studies on cardiovascular disease and obesity. The study evaluates 8 research studies to with a total sample of over 300 participants. Lastly, Simmonds et al. (2016) conducted a meta-analysis that included 15 cohort studies with a total sample size of 200,777 participants.
The remaining literature includes primary studies. Oelscher et al. (2015) conducted a primary study with 576 children between 2 and 12 years as the participants. Allender et al. (2016) also did a primary study with a sample of 5050 children from 84 primary schools as the participants. GBD 2015 Obesity Collaborators (2017) performed a study of 67.8 million people in 175 countries across the world. Lastly, Davis et al. (2016) only had 40 Mexican American mothers as the participants of the research.