Chapter 11: Q. 52 (page 757)
How far away do you live? Conduct a follow-up analysis for the test in Exercise
We note that the expected value is higher than the observed counts of the public university for the category"over ",
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Relaxing in the sauna Researchers followed a random sample of middle-aged men from eastern Finland for up to years. They recorded how often each man went to a sauna and whether or not he suffered sudden cardiac death (SCD). The two-way table shows the data from the study.
a. State appropriate hypotheses for performing a chi-square test for independence in this setting.
b. Compute the expected counts assuming that is true.
c. Calculate the chi-square test statistic, df, and P-value.
d. What conclusion would you draw?
A random sample of traffic tickets given to motorists in a large city is examined. The tickets are classified according to the race or ethnicity of the driver. The results are summarized in the following table.
The proportion of this city's population in each of the racial/ethnic categories listed is as follows.
We wish to test : The racial/ethnic distribution of traffic tickets in the city is the same as the racial/ethnic distribution of the city's population.
Assuming is true, what is the expected number of Hispanic drivers who would receive a ticket?
a.
b.
c.
d.
e.
Fruit flies Biologists wish to mate pairs of fruit flies having genetic makeup RrCc, indicating that each has one dominant gene (R) and one recessive gene (r) for eye color, along with one dominant (C) and one recessive (c) gene for wing type. Each offspring will receive one gene for each of the two traits from each parent, so the biologists predict that the following phenotypes should occur in a ratio of
Assume that the conditions for inference are met. Carry out a test at the significance level of the proposed genetic model.
Sorry, no chi-square We would prefer to learn from teachers who know their subject. Perhaps even preschool children are affected by how knowledgeable they think teachers are. Assign three- and four-year-olds at random to be taught the name of a new toy by either an adult who claims to know about the toy or an adult who claims not to know about it. Then ask the children to pick out a picture of the new toy from a set of pictures of other toys and say its name. The response variable is the count of right answers in four tries. Here are the data:
The researchers report that children who were taught by the teacher claiming to be knowledgeable did significantly better (), Explain why this result isn't valid.
โWill changing the rating scale on a survey affect how people answer the question?โ To find out, the group took an SRS of students from an alphabetical roster of the schoolโs just over students. The first students chosen were asked to rate the cafeteria food on a scale of (terrible) to (excellent). The remaining students were asked to rate the cafeteria food on a scale of (terrible) to (excellent). Here are the data:
The students decided to compare the average ratings of the cafeteria food on the two scales.
a. Find the mean and standard deviation of the ratings for the students who were given the scale.
b. For the students who were given the scale, the ratings have a mean of and a standard deviation of . Since the scales differ by one point, the group decided to add to each of these ratings. What are the mean and standard deviation of the adjusted ratings?
c. Would it be appropriate to compare the means from parts (a) and (b) using a two-sample t test? Justify your answer
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