Download Homework Questions on Research Design and Experimental Methods in Statistics and more Assignments Statistics in PDF only on Docsity! Math 1530 Homework on Observational Studies and Experiments 1. In order to determine if smoking causes cancer, researchers surveyed a large sample of adults. For each adult they recorded whether the person had smoked regularly at any period in his or her life and whether the person had cancer. They then compared the proportion of cancer cases among those who had smoked regularly at some time in their lives with the proportion of cases among those who had never smoked regularly at any point in their lives. The researchers found there was a higher proportion of cancer cases among those who had smoked regularly than among those who had never smoked regularly. This is A) an observational study. B) an experiment, but not a double blind experiment. C) a double blind experiment. D) a block design. E) a completely randomized design 2)Can pleasant aromas help a student learn better? Two researchers believed that the presence of a floral scent could improve a person's learning ability in certain situations. They had twenty-two people work through a pencil and paper maze six times, three times while wearing a floral-scented mask and three times while wearing an unscented mask. The three trials for each mask closely followed one another. Testers measured the length of time it took the subjects to complete each of the six trials. They reported that, on average, the subjects wearing the floral-scented mask completed the maze more quickly than those wearing the unscented mask, though the difference was not statistically significant. This study is A) a convenience sample. B) an observational study, not an experiment. C) an experiment, but not a double blind experiment. D) a double blind experiment. E) a survey with a self selected sample 3) We are interested in predicting if the state income tax will get approved in the next election. Therefore we would like to know what percent of the population of voters favor the state income tax. That percent is : A) a sampling frame B) a random sample C) a self selected sample d) a population parameter 4) A Senator wants to know what the voters of his state think of proposed legislation on gun control. He mails a questionnaire on the subject to an SRS of 2500 voters in his state. His staff reports that 448 questionnaires have been returned, of which 343 support the legislation. The population is A) the voters in his state. B) the 448 letters received. C) the 343 letters supporting the legislation. D) the 2500 voters receiving the questionnaire. E) The staff 5) We want to know the opinion of men and women living in the state of Tennessee. In order to take a sample of 1200 people from a population, I first divide the population into men and women, and then take a simple random sample of 500 men and a separate simple random sample of 700 women. This is an example of a A) block design. B) stratified random sample. C) double blind simple random sample. D) randomized comparative experiment. E) Two stage sampling 6) A sample that does not represent the population in some important way, such as one that overlooks an important group (either because the sampling frame did not cover the whole population, or because of the way the sample was selected, or because the there was a high non-response rate or some other reason) is said to be : A) random B) simple C) biased D) representative E) systematic more questions in the back of the page
