#30, #32

In Exercises 29-32, indicate whether the observational study used is cross-sectional, retrospective, or prospective. 29. Nurses' Health Study II Phase II of the Nurses' Health Study was started in 1989 with 116,000 female registered nurses. The study is ongoing. 30. Heart Health Study Samples of subjects with and without heart disease were selected, then researchers looked back in time to determine whether they took aspirin on a regular basis. 31. Marijuana Study Researchers from the National Institutes of Health want to determine the current rates of marijuana consumption among adults living in states that have legalized the use of marijuana. They conduct a survey of 500 adults in those states. 32. Framingham Heart Study The Framingham Heart Study was started in 1948 and is ongo- ing. Its focus is on heart disease