State the type of observational study design for each of thefollowing study. (0.8 point)
a. A study investigates the risk of exposure tosecondhand smoke on childhood asthma. 5,000 children with asthmawere matched to 10,000 controls using socio-economic status. Theirparents were then asked about exposure to secondhand smoke.
b. A study compares the average proportion ofpeople who have “high” versus “low” intake of omega-3 fatty acidconsumption with the percentage of people who have high bloodpressure in different counties in California.
c. A study examines the prevalence of marijuanause among college students. Students filled an online questionnairecovering sociodemographics, sexual behaviors, alcohol and drug usehabits.
d. A study assesses the effects of vitamin Dsupplementation on risk of type 1 diabetes. 15,000 children livingin a Scandinavian country were classified as either receivingvitamin D supplements or not receiving vitamin D supplements. Thechildren were followed for 20 years and were asked each year aboutwhether or not they had developed type 1 diabetes.
