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Exam 3: Displaying and Describing Categorical Data

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Question 61

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Describe the kind of bias that might be present if the botanist decides that instead of randomly testing she'll just… a. drop grains of rice on the aerial photo of the hill and inspect the trees that had rice land on them. b. ask the farmer to choose which trees he would like tested.

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a. Large trees would be more likely to b...

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Question 62

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College students' spending A consumer group wants to see if a new education program will improve the spending habits of college students. Students in an economics class are randomly assigned to three different courses on spending habits. a. What are the experimental units? b. How many factors are there? c. How many treatments are there? d. What is the response variable?

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a. The subjects are the students in the ...

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Question 63

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The principal of a small elementary school wants to select a simple random sample of 24 students. The school has 12 classrooms with 18 students in each class. She decides to randomly select two Students from each classroom. Is this a simple random sample?

In an experiment the primary purpose of blinding is to reduce…

Grape juice and blood pressure Researchers who wanted to see if drinking grape juice could help people lower their blood pressure got 120 non-smokers to volunteer for a study. They measured each person's blood pressure and then randomly divided the subjects into two groups. One group drank a glass of grape juice every day while the other did not. After sixty days the researchers measured everyone's blood pressure again. They reported that differences in changes in blood pressure between the groups were not statistically significant. a. Was this an experiment or an observational study? Explain briefly. b. Briefly explain what "not statistically significant" means in this context. c. Briefly explain why the researchers randomly assigned the subjects to the groups. d. Since everyone's blood pressure was measured at the beginning and at the end of the study, the researchers could have simply looked at the grape juice drinkers to see if their blood pressure changed. Briefly explain why the researchers bothered to include the control group. e. Briefly explain why the researchers studied only non-smokers. f. Other researchers now plan to replicate this study using both smokers and non-smokers. Briefly describe the design strategy you think they should use.

Researchers plan to investigate a new medication that may reduce blood pressure for individuals with higher than average blood pressure. 90 volunteers with higher than average blood pressure are solicited. Volunteers are randomly assign 100 mg of the medicine, 200 mg of the medicine, or a placebo. Blood pressure will be measured at the beginning and at the conclusion of the study. -Identify the treatments.

On January 1 of every year, many people watch the Rose Parade on television. The week before the parade is very busy for float builders and decorators. Roses, carnations, and other flowers are purchased from around the world to decorate the floats. Based on past experience, one float decorator found that 10% of the bundles of roses delivered will not open in time for the parade, 20% of the bundles of roses delivered will have bugs on them and be unusable, 60% of the bundles of roses will turn out to be beautiful, and the rest of the bundles of roses delivered will bloom too early and start to discolor before January 1. Conduct a simulation to estimate how many roses the float decorator will need to purchase to have 15 good bundles of roses to place on the float. -Show three trials by clearly labeling the random number table given below. Specify the outcome for each trial. $\begin{array}{lllllllllll}37542 & 04805 & 64894 & 74296 & 24805 & 24037 & 20636 & 10402 & 00822 \\ 08422 & 68953 & 19645 & 09303 & 23209 & 02560 & 15953 & 34764 & 35080 \\ 99019 & 02529 & 09376 & 70715 & 38311 & 31165 & 88676 & 74397 & 04436 \\ 12807 & 99970 & 80157 & 36147 & 64032 & 36653 & 98951 & 16877 & 12171\end{array}$

Researchers plan to investigate a new medication that may reduce blood pressure for individuals with higher than average blood pressure. 90 volunteers with higher than average blood pressure are solicited. Volunteers are randomly assign 100 mg of the medicine, 200 mg of the medicine, or a placebo. Blood pressure will be measured at the beginning and at the conclusion of the study. -Describe an advantage of the placebo.

Does Procellera® Antimicrobial Wound Dressing help injuries heal faster? Researchers checked records of 38 patients who had been treated for acute or chronic wounds between 2010 and 2012. They found that those who had been treated with Procellera® healed almost twice as fast. This is a

A group of people are concerned that the coach of a local high school men's and women's basketball teams alters the amount of air in the basketball to gain an unfair advantage over opponents during home games. The idea is that the basketballs are pumped up with one pound per square inch less air than required, and his teams practiced with these altered balls all week prior to home basketball games. Since these under-pumped basketballs would react differently to being shot at a basket, the team that practiced with these balls would have an unfair advantage when it came to shooting free throws. -Describe how to use a retrospective study to determine if the home teams have an unfair advantage when shooting free-throws.