1. Determine whether the study is an observational study or a controlled (10pts)
ID: 3175750 • Letter: 1
Question
1. Determine whether the study is an observational study or a controlled (10pts) experiment. Explain your answer.
a) A student watched picnickers with a large cooler of soft drinks to see whether teenagers were less likely than adults to choose diet soft drinks over regular soft drink.
b) Patients with Alzheimer’s disease were randomly divided into two groups. One group was given a new drug, and the other was given a placebo. After six months they were given a memory test to see whether the new drug fights Alzheimer’s better than a placebo. The test results showed that patients in the drug group had on average less number of symptoms of Alzheimer’s disease. Can we conclude that the new drag caused this improvement?
2). Imagine you work in a real estate agency. You need to estimate the mean (10pts) price of a one-bedroom condo in Studio City. You have a directory of all 1,000 one-bedroom condos in Santa Clarita. Which sampling method would you use and why (Random, Cluster, etc.)? How would you set it up? Explain.
Explanation / Answer
a) A student watched picnickers with a large cooler of soft drinks to see whether teenagers were less likely than adults to choose diet soft drinks over regular soft drink.
This is an observational study as the student is simply watching and is not assigning treatments to the subjects. experiments involves assigning treatments to the subjects
b) Patients with Alzheimer’s disease were randomly divided into two groups. One group was given a new drug, and the other was given a placebo. After six months they were given a memory test to see whether the new drug fights Alzheimer’s better than a placebo. The test results showed that patients in the drug group had on average less number of symptoms of Alzheimer’s disease. Can we conclude that the new drag caused this improvement?
This is a experimental study , as a treatment in the form of new drug and placebo is being administered to the 2 groups hence this is a experimental study and not an observational study
2 )
If geography of the location of the condos are not considered then a random sampling would help. However , if Santa clarita has a diverese geography in the form of mountains , riverside , etc then we can clusted the condos based on the geographical location of the condos and then do a random sampling of condos within each cluster to arrive at the mean price of the condos
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