name the population, sample, treatments, and reponse variable for the following study:
Lipitor is a cholesterol-lowering drug by pfizer. In the collaborative atrovastatin diabetes study, the effect of lipitor on cardiovascular disease was assessed in 2838 subjects aged 40-75, with type-2 diabetes, without prior history of cardiovascular disease. In this placebo-controlled, double blind experiment, subjects were randomly allocated to either lipitor 10mg daily (1429) or placebo (1411) and were followed for 4 years. The response variable was the occurrence of any major cardiovascular event.
Population: subjects aged 40-75 w/type-2 diabetes and no prior history of cardiovascular disease.
Sample: 2838 subjects aged 40-75 with/type 2 diabetes w/out history of cardiovascular disease
Treatments: 10mg lipitor daily, placebo daily for 4 years
Response variable: occurrence of any major cardiovascular event