1. Journal Club Notes

2. Learning Objectives
Review the data tables and statistical methods used in the assigned article
Choose the proper statistical tests based on the distributions of the variable and on the cell sizes in the contingency tables
Interpret unadjusted and adjusted Odds Ratios
Explain how history is a threat to the validity of a study and what can be done to address this

3. Feldman et al, “Gestational Diabetes Screening: The International Association of the Diabetes and Pregnancy Study Groups Compared with Carpenter-Coustan Screening”, Obstetrics and Gynecology, vol. 127, no. 1, January 2016.

4. Common Statistical Tests
Compare means of two groups
T-test if normally distributed
Nonparametric tests if not normally distributed
Wilcoxon test, Mann Whitney U test
Compare proportions of two or more groups
Chi-square test is most common
If any of the cells in the contingency table (e.g., 2x2 table) is less than 5 then Fisher Exact test is used

5. Wilcoxon test
Fisher Exact test

6. Fisher Exact Test
Wilcoxon test

7. All outcomes are proportions so Fisher exact test used

8. Multivariate analyses
Bivariate analyses
Not conventional

9. Look at the magnitude of these ORs. Are they clinically significant?

10. Study Design Consideration
One threat to the validity of a study is history
History refers to something else that occurs at the same time as your intervention that may affect the outcome
How do you determine whether your intervention makes a difference?
Importance of a control group
What the is control group in this study?