Exam 5: Statistical Reasoning

Determine whether the study involves selection bias, participation bias, both selection bias and participation bias, orneither. -You are interested in the degree of satisfaction amongst customers at your video store. For one week, you hand a customer satisfaction questionnaire to every customer who comes into the store And ask them to fill it out and place it in a box after they check out.

State whether the scatter diagram shows strong positive correlation, weak positive correlation, strong negativecorrelation, weak negative correlation, or no correlation. -

A statement is made about correlation. State whether the correlation is positive or negative and whether the correlation ismost likely due to coincidence, a common underlying cause, or a direct cause. -People who take more vacations score higher on standardized tests.

Solve the problem. -For the study described below, identify the population parameter. A researcher is interested in the level of stress among emergency-room nurses in the U.S. 275 emergency-room nurses were interviewed to determine their level of stress. Each nurse was assigned a stress rating based on his or her answers to a number of questions. The average stress rating for the 275 nurses was determined.

Identify which of these types of sampling is used: simple random, stratified, systematic, or convenience. -A tax auditor selects every 1000th income tax return that is received.

Use the guidelines to evaluate the study. From the information given, what is the biggest flaw in the study? -A researcher randomly selected 500 college students and asked "How many IQ points would you sacrifice to become better looking?". The following conclusion was published in the student Newspaper "Students would sacrifice 18 IQ points to be better looking."

Determine whether the study involves selection bias, participation bias, both selection bias and participation bias, orneither. -"38% of adults in the United States regularly visit a doctor". This conclusion was reached by a college student after she had questioned 520 randomly selected members of her college.

Identify which of these types of sampling is used: simple random, stratified, systematic, or convenience. -49 students are selected at random from the Sophomore class, 39 from the Junior class, and 48 from the Senior classes.

Use the guidelines to evaluate the study. From the information given, what is the biggest flaw in the study? -"38% of adults in the United States regularly visit a doctor". This conclusion was reached by a college student after she had questioned 520 randomly selected members of her college. What is Wrong with her survey?

State whether you think that the variables have strong positive correlation, weak positive correlation, strong negativecorrelation, weak negative correlation, or no correlation. -Time spent walking and distance walked

A sample statistic and margin of error are given. Find the confidence interval likely to contain the population parameterof interest and answer the question. -In a survey conducted in a certain city it was found that 4.6% of men and 5.4% of women were unemployed. The margin of error for each report was 0.6 percentage points. Use each sample Statistic to find a confidence interval. Can we conclude that the unemployment rate is higher Amongst women than amongst men?

A statement is made about correlation. State whether the correlation is positive or negative and whether the correlation ismost likely due to coincidence, a common underlying cause, or a direct cause. -Over the last 10 years in this town, as the amount of open space has decreased, consumer spending has increased.

Solve the problem. -For the study described below, identify the population. 1500 American women working for large companies were polled to determine the percentage that Felt that women were under represented in management positions in their company.

The graph below shows the approximate annual percentage growth rate in world population for the years 1960 through 2010. Data is estimated by the UN Census Bureau. Use the graph to answer the question. -Describe the trend in world population during the period 1990-2000

Construct a pie chart representing the given data set. -Intended major of high school students: Science: 32\% Social Science: 8\% Humanities: 20\% Business: 16\% Other: 24\%

State whether you think that the variables have strong positive correlation, weak positive correlation, strong negativecorrelation, weak negative correlation, or no correlation. -Age and remaining life expectancy.

Answer as requested. -A researcher finds a positive correlation between the amount of wine people drink and the number of friends they have. Which of the following statements must be true? More than one statement May be true. A: People who drink more tend, on average, to have more friends. B: If a person starts drinking more wine, they are likely to find themselves with more friends. C: If a person stops drinking wine, they are likely to find themselves with fewer friends. D: If Anna has more friends then Pierre, she must drink more wine than Pierre.

Answer the question. -Which type of graphs can be difficult to interpret because of visual distortion on a flat page?

Use the guidelines to evaluate the study. Discuss flaws that you see in the study. -A pharmaceutical company wants to test its new medication to lower blood pressure. It randomly selects 1000 people with high blood pressure and randomly assigns each person to one of two groups. The first group receives the medication for a month and also suggestions as to how to improve their diet. The control group receives a placebo medication and no dietary suggestions. At the end of the month each person's blood pressure is again taken. The average change in blood pressure is compared for the two groups.

Provide an appropriate response. -Shortly before an election, a market research firm took a poll to find out whether people were planning to vote for or against a particular ballot measure. The results are shown below. Position Frequency Against 3087 In favor 3691 Undecided 910 The ballot measure will pass if a simple majority (more than 50%)vote in favor of the measure. You wish to construct a graph to represent the data. It should be easy to see from your graph whether more than 50% of the people are planning to vote in favor of the measure. Which graph would be more useful, a bar graph or a pie chart? Explain your thinking.