1. Choose the study design that best matches each measure of disease frequency or association listed below. The study design may be used more than once or none at all. 

The measure of Frequency/Association	Study Design
____ Correlation Coefficient	Case-Control
____ Incidence Rate & Incidence Density (without intervention)	Cross-sectional
____ Relative Risk in treatment vs control group	Ecological
____ Odds Ratio of Exposure	Cohort
____ Prevalence of Disease (snapshot)	Randomized Clinical Trial
____ Relative difference between treatments
____ Prevalence Rate Ratio
____ Rate Ratio & Risk Ratio (without intervention)
____ Odds Ratio of Disease
____ Prevalence Odds Ratio