Author: Christine Farr


. Many drug safety research studies are sponsored by pharmaceutical companies that would financially benefit if the results of the study are favorable. Is this an example of a potential confounding factor? Explain?
2. Below are some data from 2005 for on the job deaths in some dangerous jobs. Which job seems the most dangerous? Which seems the least dangerous? Explain. SEE ATTACHMENT FOR DATA
3. A recent Harvard Business Review article titled, When to Sleep on it” discusses the usefulness of deliberating a business decision. The article describes a study in which subjects were asked to make a number of decisions and each subject was given the option to decide immediately or deliberate while performing an unrelated task. The researchers found that subjects who answered immediately made the best decisions and that “the longer our participants thought about their answers, the more likely they were to include irrelevant information at the expense of relevant information”. The article concludes that “conscious deliberation, however long and careful, can be a surprisingly crude and ineffective tool.”
3A. Is this study observational or experimental? Why?
3B. Can you think of a confounding factor here? 
3C. If you could re-design this study, how would you do it?
4.The file stockprices.xls (an excerpt is in Table 12.2) contains the daily closing prices for 100 different stocks over a thirty-day period. Which stock showed the most price variability? Which stock had the highest average price? SEE ATTACHMENT FOR EXHIBIT
5. The file ordersizes.xls (an excerpt is in Table 2.14) contains the dollar amounts of a large number of orders made at a company. Describe the histogram for this data SEE ATTACHMENT FOR EXHIBIT
6. Investment A has an expected return of $25 million and investment B has an expected return of $5 million. Market risk analysts believe the stand deviation of the return from A is $10 million, and for B is $30 million (negative returns are possible here).
6A. If you assume returns follow a normal distribution, which investment would give a better chance of getting at least a $40 million return? Explain
6B. How could your answer to part a) change if you knew returns followed a skewed distribution instead of a normal distribution? Explain briefly
7.You are trying to get an important new customer to buy a product that you produce. Their decision to buy the product from you will depend primarily on the speed with which you can produce the product once they have placed an order. Currently, it takes you 70 hours on average to produce the product with a stand deviation of 8 hours. From historical data, you have determined that actual production times follow a normal distribution.
7A. What percent of the time can you produce the product within 80 hours?
7B. You want to promise that 95% of the time you will deliver the product in under ____ hours. What number should you put in the blank?
7C. Assuming the standard deviation stays the same, how much do you have to reduce your average production time so that 95% of the time you can deliver the product in under 75 hours?
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