No Variation in a Sample An experiment was conducted to test the effects of alcohol. Re-searchers measured the breath alcohol levels for a treatment group of people who drank ethanol and another group given a placebo. The results are given below (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). Use a 0.05 significance level to test the claim that the two sample groups come from populations with the same mean.
Treatment Group: n1 = 22,
Placebo Group: n2 = 22,
Want to see the full answer?
Check out a sample textbook solutionChapter 9 Solutions
Elementary Statistics Plus MyLab Statistics with Pearson eText -- Title-Specific Access Card Package (13th Edition)
- Sociodemographic differences in lung cancer worry. Hahn (2017) evaluated sociodemographic differences in how people worry about lung cancer. Some of the differences observed across demographic of interest were between males and females [t[45]=0.69; higher mean worry among men], smokers and nonsmokers [t[45]=2.69; higher mean worry among smokers]. However, at least one of these results were not statistically significant. Use the information provided to state which t test or t test did not reach the .05 level of significance in this study. (a) Compute the proportion of variance using omega-squared. (b) Suppose the pooled sample standard deviation for this test is 0.74. Using this value, compute estimated Cohen's d.arrow_forwardPassive exposure to environmental tobacco smoke has been associated with growth suppression and an increased frequency of respiratory tract infections in normal children. Is this association more pronounced in children with cystic fibrosis? To answer this question, 43 children (18 girls and 25 boys) attending a 2-week summer camp for cystic fibrosis patients were studied (New England Journal of Medicine, Sept. 20, 1990). Among several variables measured were the child's weight percentile (y) and the number of cigarettes smoked per day in the child's home (x). a. For the 18 girls, the coefficient of correlation between y and x was reported as r = –.50. Interpret - this result. b. Refer to part a. The p-value for testing Ho: p = 0 against H;: p # 0 was reported as p = .03. n Interpret this result. c. For the 25 boys, the coefficient of correlation between y and x was reported asr = -.12. Interpret %3D %3D this result. d. Refer to part c. The p-value for testing Ho: p = 0 against Ha: p #…arrow_forwardHypnosis and Pain. In the paper “An Analysis of Factors That Contribute to the Efficacy of Hypnotic Analgesia” (Journal of Abnormal Psychology, Vol. 96, No. 1, pp. 46–51), D. Price and J. Barber examined the effects of hypnosis on pain. They measured response to pain using a visual analogue scale (VAS), in centimeters, where higher VAS indicates greater pain. VAS sensory ratings were made before and after hypnosis on each of 16 subjects. A hypothesis test is to be performed to decide whether, on average, hypnosis reduces pain. a. identify the variable. b. identify the two populations. c. identify the pairs. d. identify the paired-difference variable. e. determine the null and alternative hypotheses. f. classify the hypothesis test as two tailed, left tailed, or right tailed.arrow_forward
- A recent study investigated whether the number of positive health behaviors (e.g., exercising, eating healthy) is predictive of a person's score on a happiness index, such that as positive health behaviors go up, happiness goes up. The results from the study, which was conducted with 12 people, were as follows: r = 0.63 and SSY = 56.0. What is the MSregression? What is the MSresidual? What is the calculated test statistic? Given the value of your calculated test statistic and your critical test statistic, do you reject the null?arrow_forwardA data set from a study that examined the effect of a specific diet on blood pressure is provided . Participants (n = 72) were randomly assigned either to a group that was put on the diet (Diet = Present) or to a group that was not put on the diet (Diet = Absent), and researchers wanted to know whether the diet had a significant impact on blood pressure. Fully interpret the results in the context of this study (i.e., report the conclusions as related to the research question).arrow_forwardFemale college student participation in athletics has increased dramatically over the past few decades. Sports medicine providers are aware of some unique health concerns of athletic women, including disordered eating. A study compared disordered-eating symptoms and their causes for collegiate female athletes (in lean and non lean sports) and nonathletes. The sample mean of the body dissatisfaction assessment score was 13.4 (s=7.9) for 15 lean sports athletes (those sports that place value on leanness, including distance running, swimming, and gymnastics) and 7.4 (s=5.8) for the 67 non-lean athletes. Assume equal population standard deviations. Find the standard error for comparing the means. Construct a 95% confidence interval for the difference between the mean body dissatisfaction for lean sport athletes and non lean sport athletes. Interpret.arrow_forward
- To illustrate the effects of driving under the influence of alcohol, a police officer brought a DUI simulator to a high school. Student reaction time in an emergency was measured with unimpaired vision and also while wearing special goggles to simulate the effect of alcohol on vision with the following results: Normal: 4.47, 4.24, 4.58, 4.65, 4.31, 4.8, 4.55, 5, 4.79 Impaired: 5.77, 5.67, 5.51, 5.32, 5.83, 5.49, 5.23, 5.61, 5.63 Is there evidence to suggest that there is a difference at alpha = 0.05level of significance.arrow_forwardA well-known psychologist has established what she calls her Generalized Anxiety (GA) scale. The GA scale, which is a scale from 0 to 10, measures the "general anxiety" of an individual, with higher GA scores corresponding to more anxiety. We'd like to make predictions about individuals' sleep behavior based on their GA scores. We've collected bivariate data that give the GA score (denoted by x) and the number of hours of sleep last night (denoted by y) for each of the 11 adults participating in a study. The least-squares regression equation for our data is y = 8.92-0.25x. We have used this equation to predict tonight's sleep time for a woman whose GA score is 6.2. We're now interested in both a prediction interval for her sleep time and a confidence interval for the mean sleep time of individuals with her GA score. We have computed the following for our data. • mean square error (MSE)≈ 0.601 (6.2-x)² ● 11 + 11 2 Σ (x₁ - x)² i=1 ≈ 0.1110, where x₁, x2, Lower limit: X11 Based on this…arrow_forwardFoot ulcers are a common problem for people with diabetes. Higher skin temperatures on the foot indicate an increased risk of ulcers. The article "An Intelligent Insole for Diabetic Patients with the Loss of Protective Sensation" (Kimberly Anderson, M.S. Thesis, Colorado School of Mines), reports measurements of temperatures, in °F, of both feet for 181 diabetic patients. The results are presented in the following table. Left Foot Right Foot 80 80 85 85 75 80 88 86 89 87 87 82 78 78 88 89 89 90 76 81 89 86 87 82 78 78 80 81 87 82 86 85 76 80 88 89 Construct a scatterplot of the right foot temperature (y) versus the left foot temperature (x). Verify that a linear model is appropriate. b. Compute the least-squares line for predicting the right foot temperature from the left foot temperature. If the left foot temperatures of two patients differ by 2 degrees, by how much would you predict their right foot temperatures to differ? Predict the right foot temperature for a patient whose left…arrow_forward
- What is the MS between and MS within? what is the MS subject? what is the Sm (needed in the Tukey test)arrow_forwardBlood cocaine concentration (mg/L) was determinedboth for a sample of individuals who had died fromcocaine-induced excited delirium (ED) and for a sampleof those who had died from a cocaine overdose withoutexcited delirium; survival time for people in bothgroups was at most 6 hours. The accompanying datawas read from a comparative boxplot in the article“Fatal Excited Delirium Following Cocaine Use” (J.of Forensic Sciences, 1997: 25–31). ED 0 0 0 0 .1 .1 .1 .1 .2 .2 .3 .3.3 .4 .5 .7 .8 1.0 1.5 2.7 2.83.5 4.0 8.9 9.2 11.7 21.0Non-ED 0 0 0 0 0 .1 .1 .1 .1 .2 .2 .2.3 .3 .3 .4 .5 .5 .6 .8 .9 1.01.2 1.4 1.5 1.7 2.0 3.2 3.5 4.14.3 4.8 5.0 5.6 5.9 6.0 6.4 7.98.3 8.7 9.1 9.6 9.9 11.0 11.512.2 12.7 14.0 16.6 17.8 a. Determine the medians, fourths, and fourth spreadsfor the two samples.b. Are there any outliers in either sample? Any extremeoutliers?c. Construct a comparative boxplot, and use it as abasis for comparing and contrasting the ED andnon-ED samples.arrow_forwardAn experiment was conducted to compare anxiety levels among children induced between looking at snakes and pictures of snakes. The following data were collected from a sample of 10 children with orphidiophobia (fear of snakes). Use a =1.01. PARTICIPANT 1 Anxiety 4 10 5 25 6 7 8 20 25 30 30 35 50 55 40 25 score (real snakes) Anxiety 15 20 35 35 20 32 48 50 40 35 Score (pictures) Is there a significant difference between the anxiety scores of looking at real snakes or pictures of snakes? |arrow_forward
- Glencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw HillBig Ideas Math A Bridge To Success Algebra 1: Stu...AlgebraISBN:9781680331141Author:HOUGHTON MIFFLIN HARCOURTPublisher:Houghton Mifflin Harcourt