MATLAB: An Introduction with Applications
MATLAB: An Introduction with Applications
6th Edition
ISBN: 9781119256830
Author: Amos Gilat
Publisher: John Wiley & Sons Inc
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Tobacco companies have actively attempted to remake their public image by launching a youth smoking prevention advertisement campaign. Melanie
Wakefield (a professor of applied psychology and researcher at the Center for Behavioral Research in Cancer in Victoria, Australia) and her colleagues
conducted a study to assess the relation between exposure to tobacco companies' youth smoking prevention advertising and youth smoking-related
beliefs, intentions, and behaviors.
You use Professor Wakefield's research to design an experiment with two groups of middle school students from Morocco. You show the tobacco
company's youth smoking prevention ads to one of the groups of students every day for a week at the beginning of their math class. After the week,
you assess the groups on the degree to which the students approve/disapprove of teens smoking, using a 5-point Likert scale. You do not have a
prediction about the effect of the ads, as they are supposed to prevent smoking, but Professor Wakefield's findings suggested the ads might have the
opposite effect if they have any effect at all.
There are 81 students in each group. The first group, who saw the ads, scored an average of 3.4 with a sample standard deviation of 1.2 on the 5-
point Likert scale. The second group, who did not see the ads, scored an average of 2.6 with a sample standard deviation of 1.4 on the 5-point Likert
scale.
You find that the estimated standard error of the difference in means is 0.2049, the estimated Cohen's d is
the t statistic is 3.90, and the
r2 is v
Using Cohen's d and Cohen's criteria for evaluating Cohen's d, this is a
effect size. Using r? and Cohen's criteria for evaluating
r2, this is a
v effect size.
Hint: There is some subjectivity when applying verbal labels to numerical values. If the Cohen's d or r? value falls between two categories,
acknowledge both categories-for example, small to medium if it is between small and medium.
expand button
Transcribed Image Text:Tobacco companies have actively attempted to remake their public image by launching a youth smoking prevention advertisement campaign. Melanie Wakefield (a professor of applied psychology and researcher at the Center for Behavioral Research in Cancer in Victoria, Australia) and her colleagues conducted a study to assess the relation between exposure to tobacco companies' youth smoking prevention advertising and youth smoking-related beliefs, intentions, and behaviors. You use Professor Wakefield's research to design an experiment with two groups of middle school students from Morocco. You show the tobacco company's youth smoking prevention ads to one of the groups of students every day for a week at the beginning of their math class. After the week, you assess the groups on the degree to which the students approve/disapprove of teens smoking, using a 5-point Likert scale. You do not have a prediction about the effect of the ads, as they are supposed to prevent smoking, but Professor Wakefield's findings suggested the ads might have the opposite effect if they have any effect at all. There are 81 students in each group. The first group, who saw the ads, scored an average of 3.4 with a sample standard deviation of 1.2 on the 5- point Likert scale. The second group, who did not see the ads, scored an average of 2.6 with a sample standard deviation of 1.4 on the 5-point Likert scale. You find that the estimated standard error of the difference in means is 0.2049, the estimated Cohen's d is the t statistic is 3.90, and the r2 is v Using Cohen's d and Cohen's criteria for evaluating Cohen's d, this is a effect size. Using r? and Cohen's criteria for evaluating r2, this is a v effect size. Hint: There is some subjectivity when applying verbal labels to numerical values. If the Cohen's d or r? value falls between two categories, acknowledge both categories-for example, small to medium if it is between small and medium.
Dr. Park is interested in how the functioning of the brain changes with age and how this, in turn, affects older individuals' memory abilities. She
randomly selects 11 older and 16 younger adults to study pictures of landscapes presented for 5 seconds each. After a 10-minute rest period, both
groups perform a visual recognition test. They view a series of pictures and categorize each as either "old" (part of the set they studied) or "new"
pictures. While this test is occurring, researchers use FMRI to measure the participants' brain activity. Dr. Park and her team notice that the older
adults all produced similar amounts of activity during the task. The younger adults, on the other hand, showed much more diversity of brain activity.
Some younger study participants had a large amount of activity, while others had much less.
Would it be valid for Dr. Park to use the independent-measures t test to test whether the brain activity of younger adults is different from that of older
adults during a visual recognition task?
O Yes, because none of the assumptions of the independent-measures t test are violated.
No, because the two populations from which the samples are selected do not appear to have equal variances.
O No, because the two groups studied are not independent.
O Yes, because the independent-measures t test is a robust test.
expand button
Transcribed Image Text:Dr. Park is interested in how the functioning of the brain changes with age and how this, in turn, affects older individuals' memory abilities. She randomly selects 11 older and 16 younger adults to study pictures of landscapes presented for 5 seconds each. After a 10-minute rest period, both groups perform a visual recognition test. They view a series of pictures and categorize each as either "old" (part of the set they studied) or "new" pictures. While this test is occurring, researchers use FMRI to measure the participants' brain activity. Dr. Park and her team notice that the older adults all produced similar amounts of activity during the task. The younger adults, on the other hand, showed much more diversity of brain activity. Some younger study participants had a large amount of activity, while others had much less. Would it be valid for Dr. Park to use the independent-measures t test to test whether the brain activity of younger adults is different from that of older adults during a visual recognition task? O Yes, because none of the assumptions of the independent-measures t test are violated. No, because the two populations from which the samples are selected do not appear to have equal variances. O No, because the two groups studied are not independent. O Yes, because the independent-measures t test is a robust test.
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