Researchers were interested in determining if lifestyle modification can reduce the incidence of a second heart attack (myocardial infarction). They identified a group of 700 patients who had a first (single) heart attack within the past five years.  These patients were then randomly allocated to: 1) a lifestyle intervention group (n=350) that received intensive dietary and physical activity counseling and training; or 2) a comparison group (n=350) that received only some educational information regarding the benefits of healthy lifestyles in reducing heart disease. These groups were then followed for 5 years to determine the rates of second heart attacks.  The researchers could use a triple masked (blind) study design

Currently, when testing in the community, the CDC COVID-19 PCR screening test is estimated to correctly identify 70% to 80% of all true COVID-19 positive individuals.  What does this statement relative to?   

Policies, procedures, and threshold levels of a screening test should be determined in advance to establish who should be referred for further testing, diagnostics and possible treatment. Once these are determined in at least one study population, the screening test can be administered on any population in the world.

Many large community intervention studies often use cluster sampling.

The unexposed group (comparison group) should be as similar as possible to the exposed group in a cohort study. This is why researchers used randomization at the start of the study.

Very small trials to determine the safety and safe dose of an experimental drug are what kind of trials:

Post marketing surveillance refers to what kind of trial?

Non-compliance in taking treatment or control group medications in clinical trials will increase the statistical power to detect a difference in treatments.

The figure shown above is an example of what kind of randomized controlled trial design?

Researchers at the Novo Nordisk Pharmaceutical Company are interested in determining the effectiveness of a new (untested) long-acting insulin for type 1 diabetes treatment. In the study, is it ethical to use a placebo?