Researchers conducted an experiment to test the effects of alcohol. Errors were recorded in a test of visual and motor skills for a treatment group of 23 people who drank ethanol and another group of 23 people given a placebo. The errors for the treatment group have a standard deviation of 2.10, and the errors for the placebo group have a standard deviation of 0.75. Use a 0.05significance level to test the claim that the treatment group has errors that vary significantly more than the errors of the placebo group. Assume that the two populations are normally distributed. Identify the test statistic. = (Round to two decimal places as needed.) Use technology to identify the P-value. = (Round to three decimal places as needed.)
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10 \) and \( s_2 = 0.75 \). \[ F = \frac{2.10^2}{0.75^2} = \frac{4.41}{0.5625} = 7.84 \] Show more…
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Test the given claim. Researchers conducted an experiment to test the effects of alcohol. Errors were recorded in a test of visual and motor skills for a treatment group of 22 people who drank ethanol and another group of 22 people given a placebo. The errors for the treatment group have a standard deviation of $2.20,$ and the errors for the placebo group have a standard deviation of 0.72 (based on data from "Effects of Alcohol Intoxication on Risk Taking. Strategy, and Error Rate in Visuomotor Performance," by Streufert et al., Joumal of Applied Psychology, Vol. 77, No. 4). Use a 0.05 significance level to test the claim that the treatment group has errors that vary significantly more than the errors of the placebo group.
Inferences from Two Samples
Two Variances or Standard Deviations
An experiment was conducted to test the effects of alcohol. Researchers measured the breath alcohol levels for a treatment group of people who drank ethanol and another group given a placebo. The results are given in the accompanying table. Use a 0.05 significance level to test the claim that the rwo sample groups come from populations with the same mean. The given results are based on data from "Effects of Alcohol Intoxication on Risk Taking, Strategy, and Error Rate in Visuomotor Performance," by Streufert, et al., Journal of Applied Psychology VoL 77, No. 4. Treatment Group: $\quad n_{1}=22 \quad \bar{x}_{1}=0.049 \quad s_{1}=0.015$ Placebo Group: $n_{2}=22 \quad \bar{x}_{2}=0.000 \quad s_{2}=0.000$
Inference From Two Samples
Inferences About Two Means: Independent Samples
Test the given claim. Identify the null hypothesis, alternative hypothesis, test statistic, P-value or critical value(s), then state the conclusion about the null hypothesis, as well as the final conclusion that addresses the original claim. In a study of treatments for very painful "cluster" headaches, 150 patients were treated with oxygen and 148 other patients were given a placebo consisting of ordinary air. Among the 150 patients in the oxygen treatment group, 116 were free from headaches 15 minutes after treatment. Among the 148 patients given the placebo, 29 were free from headaches 15 minutes after treatment (based on data from "High-Flow Oxygen for Treatment of Cluster Headache," by Cohen, Burns, and Goads by, Journal of the American Medical Association, Vol. $302,$ No. 22 ). We want to use a 0.01 significance level to test the claim that the oxygen treatment is effective. a. Test the claim using a hypothesis test. b. Test the claim by constructing an appropriate confidence interval. c. Based on the results, is the oxygen treatment effective?
Two Proportions
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