Sample surveys for sensitive issues. It is difficult to conduct sample surveys on sensitive issues because many people will not answer questions if the answers might embarrass them. Randomized response is an effective way to guarantee anonymity while collecting information on topics such as student cheating or sexual behavior. Here is the idea. To ask a sample of students whether they have plagiarized a term paper while in college, have each student toss a coin in private. If the coin lands heads and they have not plagiarized, they are to answer No. Otherwise, they are to give Yes as their answer. Only the student knows whether the answer reflects the truth or just the coin toss, but the researchers can use a proper random sample with followup for nonresponse and other good sampling practices. Suppose that in fact the probability is 0.3 that a randomly chosen student has plagiarized a paper. Draw a tree diagram in which the first stage is tossing the coin and the second is the truth about plagiarism. The outcome at the end of each branch is the answer given to therandomized-response question. What is the probability of a No answer in the randomized-response poll? If the probability of plagiarism were 0.2, what would be the probability of a No response on the poll? Now suppose that you get 39% No answers in a randomized-response poll of a large sample of students at your college. What do you estimate to be the percent of the population whohave plagiarized a paper?

Week 10 & 11: Confidence Intervals for Means Point estimate +- margin of error o Choose the appropriate statistic and its corresponding margin of error based on the problem that is to be solved “margin of error” for estimating the True Mean of a population MOE at 95% confidence= the amount that when added and subtracted to the true population mean will define a region that will include the middle 95% of all possible x-bar values Confidence vs. probability o Before a sample is collected, there is a 95% probability that the future to be computed sample mean, will fall within m.o.e. units of u o After the sample is collected, the computed