Concept explainers
The paper “Sociochemosensory and Emotional
One of the three shirts had been worn by the subject’s roommate. The subject was asked to identify the shirt worn by her roommate. This process was then repeated with another three shirts, and the number of times out of the two trials that the subject correctly identified the shirt worn by her roommate was recorded. The resulting data is given in the accompanying table.
a. Can a person identify her roommate by smell? If not, the data from the experiment should be consistent with what we would have expected to see if subjects were just guessing on each trial. That is, we would expect that the probability of selecting the correct shirt would be 1/3 on each of the two trials.
Calculate the proportions of the time we would expect to see 0, 1, and 2 correct identifications if subjects are just guessing. (Hint: 0 correct identifications occurs if the first trial is incorrect and the second trial is incorrect.)
b. Use the three proportions computed in Part (a) to carry out a test to determine if the numbers of correct identifications by the students in this study are significantly different from what would have been expected by guessing. Use α = .05. (Note: One of the expected counts is just a bit less than 5. For purposes of this exercise, assume that it is OK to proceed with a goodness-of-fit test.)
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Introduction to Statistics and Data Analysis
- A researcher is interested in the relationship between caffeine consumption and headaches in American women between the ages 25 to 50 years old. She randomly selected 512 medical records of women who suffer from headaches. She recorded if the participant did not drink caffeine, drank a moderate amount of caffeine, or drank an excessive amount of caffeine. She found that women who suffered from headaches tended to drink an excessive amount of caffeine. a. Identify the population for the study. b. Identify the sample for the study. c. Was this an observational study or a controlled experiment? Explain how you know. d. Assuming the rest of the study was well-designed, use your answers to discuss whether it would be reasonable to conclude that drinking a large quantity of caffeine will cause headaches. For the toolbar, press ALT+F10 (PC) or ALT+FN+F10 (Mac).arrow_forwardA paper described a survey of 507 undergraduate students at a state university in the southwestern region of the United States. Each student in the sample was classified according to class standing (freshman, sophomore, junior, or senior) and body art category (body piercings only, tattoos only, both tattoos and body piercings, no body art). Use the data in the accompanying table to determine if there is evidence of an association between class standing and response to the body art question. Assume that it is reasonable to regard the sample of students as representative of the students at this university. Use α = 0.01. Freshman Sophomore Junior Senior Body Piercings Only 64 44 20 21 Tattoos Only 7 11 9 17 Both Body Piercings and Tattoos 17 10 7 26 Calculate the test statistic. (Round your answer to two decimal places.) x² = | No Body Art 86 65 46 57 Use technology to calculate the P-value. (Round your answer to four decimal places.) P-value =arrow_forwardThe American Society for Microbiology (ASM) and the Soap and Detergent Association (SDA) jointly commissioned two separate studies during 2007, both of which were conducted by Harris Interactive. In one of the studies, 1001 adults were interviewed by telephone and asked about their hand-washing habits. In the other study, the hand-washing behavior of 6076 adults was inconspicuously observed within public restrooms in four U.S. cities. Address the following: a. In the telephone interviews, 921 of the adults said they always wash their hands in public restrooms. Use this result to obtain a point estimate for the proportion of adults who say they always wash their hands in public restrooms. b. Verify that the requirements for constructing a confidence interval for p from part (a) are satisfied. c. Using the results from the telephone interviews, construct and interpret a 95% confidence interval for the proportion of adults who say they always wash their hands in public restrooms. d. Is it…arrow_forward
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