Method- The purpose and population for the investigation
1. Study hypothesis
What is the study question being investigated?
2. Study population
What population is being investigated and what are the inclusion and exclusion criteria for the participants of the investigation?
3. Sample size and statistical power
How many individuals are included in the study and in the control groups? Are the numbers adequate to demonstrate statistical significance if the study hypothesis is true (what is the statistical power)?
Assignment- Selection of participants for the study and control groups
What method is used to identify and assign individuals or populations to study and control groups?
2. Confounding variables
Are there differences between study and control groups, other than the factor being investigated, that may affect the outcome of the investigation?
3. Masking or blinding
Are the participants and/or the investigators aware of the participants’ assignment to a particular study or control group?
Assessment- Measurement of outcomes or endpoints in the study and control groups
Does the measurement of outcomes address the study’s question?
2. Accurate and precise
Is the measurement of outcomes an accurate and precise measure of the phenomenon that the investigators seek to assess?
3. Complete and unaffected by observation
Is the outcome measurement nearly 100% complete and is it affected by the participants’ or the investigators’ knowledge of the study group or control group assignment?
Results- Comparison of outcomes in the study and control groups
What is the magnitude or strength of the relationship observed in the investigation?
What statistical technique(s) are used to perform statistical significance testing?
What statistical technique(s) are used to take into account or control for differences between the study group and the control group that may affect the results?
Interpretation- Meaning of the results for those included in the investigation
1. Contributory cause or efficacy
Does the factor being investigated alter the probability that the disease will occur (contributory cause) or work to reduce the probability of undesirable outcomes (efficacy)?
Are adverse events that affect the meaning of the results identified?
3. Subgroups and interactions
Do the outcomes in subgroups differ and are there interactions between factors that affect outcomes?
Extrapolation- Meaning for those not specifically included in the investigation
1. To similar individuals, groups, or populations
Do the investigators extrapolate or extend the conclusions to individuals, groups, or populations that are similar to those who participated in the investigation?
2. Beyond the data
Do the investigators extrapolate by extending the conclusions beyond the dose, duration, or other characteristics of the investigation?
3. To other populations
Do the investigators extrapolate to populations or settings that are quite different from those in the investigation?
Riegelman, R.K. & Nelson, B.A. (2021). Studying a study & testing a test. Wolters Kluwer.
Bovbjerg, M. L., Cheyney, M., & Everson, C. (January 01, 2016). Maternal and Newborn Outcomes Following Waterbirth: The Midwives Alliance of North America Statistics Project, 2004 to 2009 Cohort. Journal of Midwifery & Women’s Health, 61, 1, 11-20.