Question

Identify a type of design (e.g., randomized trial, prospective study, descriptive study, case-control study, etc). for each of the studies

Fifteen hundred adult males working for Locheed Aircraft are recruited to participate in a study of coronary heart disease. Every 3 years they are examined for new occurrences of this disease. Coronary heart disease rates are compared among groups defined by personal characteristics as they were recorded at the beginning of the study.

A random sample of middle-age sedentary females was selected from four census tracts, and each woman was examined for coronary heart disease. All those having the disease were excluded from the study. All others were randomly assigned to either an exercise group, which followed a 3-year program of systematic exercise, or a comparison group, which had no exercise program. Both groups were evaluated for coronary heart disease every 6 months and incidence of coronary heart disease compared after 3 years.                                 

Answer 1

Discriptive study is the observational initial study which check occurence of disease among a group by person place or other characteristics. So 1500 workers selected for occurence of coronary artery disease and they are compared among groups defined by personal characteristics that are recorded in early stages, check it in every 3 years so this is discriptive study. Randomized trial is a trial which help to compare and find out effectiveness of two different treatment it maybe existing treatment or a new one

Here a random sample of sedentary middle age women has taken and people already having of Coronary artery disease where excluded and others were taken ( this is called prospective or cohort study because participants are enrolled before developing disease).Then comes the randomized trial , half of that women randomly selected and given exercise regimen for 3years other half has no exercise then check occurence of coronary artery disease every 6months,then comparing results after 3 year,this randomized trial.Here one group we will keep as control and other as cases.