Introductory Statistics (2nd Edition)
2nd Edition
ISBN: 9780321978271
Author: Robert Gould, Colleen N. Ryan
Publisher: PEARSON
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Chapter 12, Problem 20SE
A Smile a Day Smiling is a sign of a good mood, but can smiling improve a bad mood? Researchers plan to assign subjects to two groups. Subjects in both groups will rate their mood at the beginning of the study. Then subjects in the treatment group will be told to smile while they are asked to recount a pleasant memory. Subjects in the control group will also be asked to recount a pleas-ant memory, but they will not be told to smile. Both groups will again rate their moods, and researchers will determine whether the reported moods differ between the two groups. Because the initial, baseline mood rating might affect the outcome, after the first mood rating the subjects will be broken into two groups: one group with low ratings (“bad mood”) and one with higher ratings (“good mood”). Patients in each group will then be randomly assigned to either the treatment group or the control group. Is this an appropriate use of blocking? If so, explain why. If not, describe a better blocking plan.
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A researcher conducts an independent-measures study examining how the brain chemical serotonin is related to aggression. One sample of rats serves as a control group and receives a placebo that does not affect normal levels of serotonin. A second sample of rats receives a drug that lowers brain levels of serotonin. Then the researcher tests the animals by recording the number of aggressive responses each of the rats display. The data are as follows.
Control Low Serotonin
n = 15 n = 20
M = 18 M = 22
SS = 172.5 SS = 135.0
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A researcher conducts an independent-measures study to examine how the brain chemical serotonin is related to aggression. One sample of rats serves as a control group and receives a placebo that does not affect normal levels of serotonin. A second sample of rats, low serotonin group, receives a drug that lowers brain levels of serotonin. Then, the researcher tests the animals by recording the number of aggressive responses each of the rats display. See the data below. Is there a significant difference between the control group and the low serotonin group regarding the number of aggressive responses?
Control Low Serotonin
n = 10 n = 15
M = 14 M = 19
SS = 180.5 SS = 130
Perform a hypothesis test using independent-measures t-test. Use a two-tailed…
Chapter 12 Solutions
Introductory Statistics (2nd Edition)
Ch. 12 - Dairy Products and Muscle The following two...Ch. 12 - Coffee and Depression The following two headlines...Ch. 12 - Prob. 3SECh. 12 - Prob. 4SECh. 12 - Prob. 5SECh. 12 - Prob. 6SECh. 12 - Niacin and Heart Disease The New England Journal...Ch. 12 - Prob. 8SECh. 12 - Prob. 9SECh. 12 - Prob. 10SE
Ch. 12 - Prob. 11SECh. 12 - Prob. 12SECh. 12 - Prob. 13SECh. 12 - Prob. 14SECh. 12 - Prob. 15SECh. 12 - Options on Global Warming People were asked...Ch. 12 - Prob. 17SECh. 12 - SAT Prep and Power Suppose an SAT tutoring company...Ch. 12 - Brain Games (Example 2) Researchers are interested...Ch. 12 - A Smile a Day Smiling is a sign of a good mood,...Ch. 12 - Swimsuits and Racing Speeds (Example 3) New, slick...Ch. 12 - Flu Vaccines and Age Suppose you want to compare...Ch. 12 - Preventing Heart Attacks with Aspirin Suppose that...Ch. 12 - Prob. 24SECh. 12 - Prob. 25SECh. 12 - Prob. 26SECh. 12 - Reading Colored Paper (Example 4) Some people...Ch. 12 - Prob. 28SECh. 12 - Prob. 29SECh. 12 - Prob. 30SECh. 12 - Prob. 31SECh. 12 - Prob. 32SECh. 12 - Prob. 33SECh. 12 - Prob. 34SECh. 12 - Prob. 35SECh. 12 - Prob. 36SECh. 12 - Prob. 37SECh. 12 - Prob. 38SECh. 12 - Prob. 39SECh. 12 - Prob. 40SECh. 12 - Prob. 41SECh. 12 - Prob. 42SECh. 12 - Prob. 43SECh. 12 - Prob. 44SECh. 12 - Prob. 45SECh. 12 - Prob. 46SECh. 12 - Prob. 47SECh. 12 - Prob. 48SECh. 12 - Prob. 49SECh. 12 - Prob. 50SECh. 12 - Alumni Donations The alumni office wishes to...Ch. 12 - Prob. 52SECh. 12 - Drug for Asthma (Example 7) Eosinophils are a form...Ch. 12 - Blood Sugar Refer to Exercise 12.50 on tight...Ch. 12 - Prob. 55SECh. 12 - Prob. 56SECh. 12 - Prob. 57CRECh. 12 - Prob. 58CRECh. 12 - Prob. 59CRECh. 12 - Prob. 60CRE
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