Stressed-Out Bus Drivers. Frustrated passengers, congested streets, time schedules, and air and noise pollution are just some of the physical and social pressures that lead many urban bus drivers to retire prematurely with disabilities such as coronary heart disease and stomach disorders. An intervention program designed by the Stockholm Transit District was implemented to improve the work conditions of the city’s bus drivers. Improvements were evaluated by G. Evans et al., who collected physiological and psychological data for bus drivers who drove on the improved routes (intervention) and for drivers who were assigned the normal routes (control). Their findings were published in the article “Hassles on the Job: A Study of a Job Intervention With Urban Bus Drivers” (Journal of Organizational Behavior, Vol. 20, pp. 199–208). Following are data, based on the results of the study, for the heart rates, in beats per minute, of the intervention and control drivers.
- a. Obtain dotplots for each of the two data sets, using the same scales.
- b. Use your result from part (a) to compare the two data sets.
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Chapter 2 Solutions
Introductory Statistics (10th Edition)
- The following data are obtained from a study that seeks to investigate theeffects of an intervention program and the extent of their physical disability on their reading, math and IQ scores. The students who had been recipients of an intervention program are in the treatment group and while those who are not are in the control group. Questions:1. Is there a significant difference in the math, reading and IQ scores ofstudents in the treatment and controlgroups?2. Is the intervention program effective?3. Is there a significant difference in the math, reading and IQ scores ofstudentswhen they are grouped according to the extent of their physicaldisability?4. Isthereasignificantinteractionbetweentreatmentandextentofdisabilityonthe students’ reading, math and IQscores?arrow_forwardIn studies examining the effect of humor on interpersonal attractions, McGee and Shevlin (2009) found that an individual’s sense of humor had a significant effect on how the individual was perceived by others. In one part of the study, female college students were given brief descriptions of a potential romantic partner. The fictitious male was described positively as being single and ambitious and having good job prospects. For one group of participants, the description also said that he had a great sense of humor. For another group, it said that he has no sense of humor. After reading the description, each participant was asked to rate the attractiveness of the man on a seven-point scale from 1 (very unattractive) to 7 (very attractive). A score of 4 indicates a neutral rating. The females who read the “great sense of humor” description gave the potential partner an average attractiveness score of M = 4.53 with a standard deviation of s = 1.04. If the sample consisted of n = 16…arrow_forwardA U.S. study published in The American Journal of Preventive Medicine compared state-level prevalence of firearm ownership in 2002 with state-level rates of firearm assault and firearm robbery in the subsequent year. The investigators found a positive association - meaning that states with higher prevalence of firearm ownership also tended to be the states with higher rates of firearm assault. Which design best describes this study? a)Observational cohort study b)Randomized trial c)Case-control study d)Ecological studyarrow_forward
- In the book Business Research Methods (5th ed.), Donald R. Cooper and C. William Emory discuss studying the relationship between on-the-job accidents and smoking. Cooper and Emory describe the study as follows: Suppose a manager implementing a smoke-free workplace policy is interested in whether smoking affects worker accidents. Since the company has complete reports of on-the-job accidents, she draws a sample of names of workers who were involved in accidents during the last year. A similar sample from among workers who had no reported accidents in the last year is drawn. She interviews members of both groups to determine if they are smokers or not. The sample results are given in the following table. On-the-Job Accident Smoker Yes No Row Total Heavy 12 5 17 Moderate 9 10 19 Nonsmoker 13 17 30 Column total 34 32 66 Expected counts are below observed counts Accident No Accident Total Heavy 12 5 17 8.76 8.24…arrow_forwardA researcher assembled two groups of individuals suffering from symptoms of the common cold. Group A was instructed to take a new supplement three times a day. Group B was simply advised to take over the counter remedies. At the end of the trial period, 90% of the individuals from Group A had less symptoms, and 25% of the individuals from Group B had less symptoms. a) Was this study observational or experimental? Why?b) What was the explanatory variable? What was the response variable?arrow_forwardSleep apnea is a disorder characterized by pauses in breathing during sleep. Children who suffer from untreated sleep apnea often have behavior problems, including hyperactivity, inattention, and aggression. A common treatment for pediatric sleep apnea is the surgical removal of enlarged tonsils and adenoids that are obstructing the airways. Suppose researchers at a sleep clinic are interested in the effect of surgical treatment for pediatric sleep apnea on aggressive behavior. They study 11 children without sleep apnea, 11 children with untreated sleep apnea, and 11 children who have been surgically treated for sleep apnea. Aggression is measured using the Conners Rating Scales. The sample means and sums of squares of the scores for each of the three groups are presented in the following table. Group Sample Mean Sum of Squares No Sleep Apnea 0.59 0.3240 Untreated Sleep Apnea 0.45 0.4410 Treated Sleep Apnea 0.31 0.2250 The researchers perform an analysis of…arrow_forward
- Reviewers from the Oregon Evidence-Based Practice Center at the Oregon Health and Science University investigated the effectiveness of prescription drugs in assisting people to fall asleep and stay asleep (source: S. Carson, M.S. McDonagh, et al., “Drug class review: Newer drugs for insomnia,” Oregon Health and Science University, 2008, http://www.ncbi.nlm.nih.gov). Suppose a study of two drugs, Sonata and Ambien, was conducted and the resulting data are contained in a file titled Shuteye. The samples reflect an experiment in which individuals were randomly given the two brands of pills on separate evenings. Their time spent sleeping was recorded for each of the brands of sleeping pills. (A) Does the experiment seem to have dependent or independent samples? Explain your reasoning. (B) Do the data indicate that there is a statistical difference in the mean time spent sleeping for people using the two drugs? Test using alpha = 0.02. Conduct a statistical procedure to determine this. (C)…arrow_forwardA study by Bettmann (2007) published in the Journal of the American Psychoanalytic Association assessed whether the attachment relationships between adolescents and their parents changed as a result of a residential wilderness treatment experience for the adolescents. Participants completed the Adolescent Attachment Questionnaire at the start and at the end of the wilderness program. Which statistical test should be used to determine whether the wilderness treatment affected attachment relationships? a. dependent-samples t test b. z test c. independent samples t-test d. one-sample t testarrow_forwardEighteen participants took part in an experimental study that consisted of three levels: normal classroom teaching, normal classroom teaching with tutors, and an experimental teaching method to increase student scores on a statistics exam. Your data set includes the following variables: Treatment (1 - normal classroom teaching; 2 - normal classroom teaching with tutors; 3 - experimental teaching method) Gender (1 – female; 2 – male) Pre-test score (higher scores represent better student performance on a statistics exam) Post-test score (higher scores represent better student performance on a statistics exam) Stanford-Binet Intelligence Test scores (IQ) The number of hours the student studied per week. Do test scores at pre-treatment differ from test scores at post-treatment? Note, this analysis should be conducted ignoring the treatment group they are in. Select an appropriate statistical test and state teh hullhypothesis.arrow_forward
- Which of the independent variables retains the strongest association with the number of children a respondent has when all other variables in the model are controlled? What is that association? Which has the weakest when other variables are controlled?arrow_forwardWhen results are not statistically significant, why do you conclude that it is plausible that the two variables are independent rather than concluding that the variables are different independent?arrow_forwardSuppose that, as part of a research methods class, Bailey was asked to write a summary of a research paper on the topic of the effects of oil contamination in soil on seed germination rates. Identify the explanatory and the response variables.arrow_forward
- Glencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw Hill