Concept explainers
Is caffeine addictive? Does the caffeine in coffee, tea. and cola induce an addiction similar to that induced by alcohol, tobacco, heroin, and cocaine? In an attempt to answer this question, researchers at Johns Hopkins University examined 27 caffeine drinkers and found 25 who displayed some type of withdrawal symptoms when abstaining from caffeine. [Note: The 27 caffeine drinkers volunteered for the study.] Furthermore, of 11 caffeine drinkers who were diagnosed as caffeine dependent, 8 displayed dramatic withdrawal symptoms (including impairment in normal
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Statistics for Business and Economics (13th Edition)
- There is a large body of literature demonstrating that early exposure to frightening movies is associated with lingering fright symptoms. As part of a class on media effects study was performed in which participants were asked to write narrative accounts of their exposure to frightening movies before the age of 13. More than one-fourth of the respondents said that some of the fright symptoms were still present in waking life. Some of the data is presented in the table: Ongoing fright symptoms No Yes Observed number of study participants Group W 50 29 c. d. Group Q 31 7 a. Construct the joint distribution of the data, and the marginal distributions. b. Construct and describe the conditional distributions for the two groups of participants. Draw a bar plot of the distributions in (b). Consider a test of association for the data in the table. State in a few words what such a test is used for. e. Perform the test in (d). State the hypotheses, test statistic, decision rule, and conclusion.arrow_forwardI need guidance on the last question listed at the end of this .... An experiment was conducted to determine if motivational techniques in management significantly affected employee stress levels compared to no intervention. An employee survey was given to three groups: one group under a manager who started using a transformational motivation technique, one group under a manager who began using a transactional motivation technique, and then a control group with no new technique used. Stress levels were self-reported by the employees on 10-point Likert scales (0 – no stress, 1- little stress, 9 – very high stress). The results are shown below. Use alpha = 0.05. Transformational Transactional Control 0 2 6 7 5 5 3 3 8 5 0 9 2 1 5 Null hypothesis: There is no significant difference in stress levels between the three groups. Alternative hypothesis: There is significance difference in stress levels between the three groups. The…arrow_forwardThe following is based on information from The Wolf in the Southwest: The Making of an Endangered Species, by David E. Brown (University of Arizona Press). Before 1918, the proportion of female wolves in the general population of all southwestern wolves was about 50%. However, after 1918, southwestern cattle ranchers began a widespread effort to destroy wolves. In a recent sample of 37 wolves, there were only 11 females. One theory is that male wolves tend to return sooner than females to their old territories, where their predecessors were exterminated. Do these data indicate that the population proportion of female wolves is now less than 50% in the region? Use α = 0.01. (a) What is the level of significance? State the null and alternate hypotheses. O Ho: P 0.5 O Ho: P = 0.5; H₁: p 5 and nq > 5. O The Student's t, since np > 5 and ng > 5. The standard normal, since np < 5 and nq < 5. O The Student's t, since np < 5 and nq < 5. What is the value of the sample test statistic? (Round…arrow_forward
- The following is based on information from The Wolf in the Southwest: The Making of an Endangered Species, by David E. Brown (University of Arizona Press). Before 1918, the proportion of female wolves in the general population of all southwestern wolves was about 50%. However, after 1918, southwestern cattle ranchers began a widespread effort to destroy wolves. In a recent sample of 37 wolves, there were only 11 females. One theory is that male wolves tend to return sooner than females to their old territories, where their predecessors were exterminated. Do these data indicate that the population proportion of female wolves is now less than 50% in the region? Use a = 0.01.arrow_forwardThe following is based on information from The Wolf in the Southwest: The Making of an Endangered Species, by David E. Brown (University of Arizona Press). Before 1918, the proportion of female wolves in the general population of all southwestern wolves was about 50%. However, after 1918, southwestern cattle ranchers began a widespread effort to destroy wolves. In a recent sample of 37 wolves, there were only 11 females. One theory is that male wolves tend to return sooner than females to their old territories, where their predecessors were exterminated. Do these data indicate that the population proportion of female wolves is now less than 50% in the region? Use a = 0.01. (a) What is the level of significance? State the null and alternate hypotheses. O Ho: p 0.5 (b) What sampling distribution will you use? O The Student's t, since np 5 and nq > 5. O The Student's t, since np > 5 and ng > 5. What is the value of the sample test statistic? (Round your answer to two decimal places.)…arrow_forwardIn a study, investigators surveyed individuals by telephone about how often they get tension headaches. One response variable that was measured was whether or not the respondent had experienced an episodic tension-type headache (ETTH) in the prior year. A headache pattern was called "episodic" if the headaches occurred less often than 15 times a month; otherwise, the headaches were called "chronic." Of the 1,660 women in the survey aged 18 to 29, a total of 658 said that they had experienced ETTHs in the last year. Of the 2,172 women in the 30- to 39-year-old age group, the number having experienced episodic headaches was 996. (a) Calculate the proportion who experienced an episodic headache in the prior year in the 18 to 29 group. (Round your answer to four decimal places.) Calculate the proportion who experienced an episodic headache in the prior year in the 30 to 39 group. (Round your answer to four decimal places.) Compute the difference in these two proportions. (Use p18…arrow_forward
- A sociologist wants to investigate the question, "Is there a relationship between texting during class and grade-point-average (GPA) among high school seniors in a large district?" Which study design is most appropriate? Before the semester starts, randomly select 40 seniors from each high school who do not text during class. Assign 20 to the texting treatment group (text three or more times during every class meeting) and 20 to the control group (no texting during class). At the end of the semester, obtain each student’s GPA from the appropriate admissions and records office. Compare the GPA of students who routinely text during class to the GPA of students who do not text during class. Before the semester starts, randomly select 40 seniors from each high school who do not text during class. Assign 20 to the texting treatment group (text three or more times during every class meeting) and 20 to the control group (no texting during class). At the end of the semester,…arrow_forward. A researcher suspects that the actual prevalence of generalized anxiety among children and adolescents is higher than the previously reported prevalence of generalized anxiety disorder among children and adolescents. The previously reported prevalence of generalized anxiety disorder among children and adolescents is 4.1%, and the researcher conducts a study to test the accuracy of the previously reported prevalence of generalized anxiety disorder by recruiting 98 children and adolescents from various pediatricians’ offices and tests them for generalized anxiety disorder using the DSM-5. The researcher determines that the prevalence of generalized anxiety disorder among the participants of the study is 6.8%. The researcher’s hypothesis, for a level of significance of 5%, should resemble which of the following sets of hypothesis? A) H0: p > .041; H1: p = .041; alpha= .05 B) H0: p > .041; H1: p = .041; alpha= .95 C) H0: p = .041; H1: p > .041; alpha= .05 D) H0: p = .041; H1: p…arrow_forward. A researcher suspects that the actual prevalence of generalized anxiety among children and adolescents is higher than the previously reported prevalence of generalized anxiety disorder among children and adolescents. The previously reported prevalence of generalized anxiety disorder among children and adolescents is 4.1%, and the researcher conducts a study to test the accuracy of the previously reported prevalence of generalized anxiety disorder by recruiting 98 children and adolescents from various pediatricians’ offices and tests them for generalized anxiety disorder using the DSM-5. The researcher determines that the prevalence of generalized anxiety disorder among the participants of the study is 6.8%. The researcher’s hypothesis, for a level of significance of 5%, should resemble which of the following sets of hypothesis? I sent a picture of the work I tried to do, I'm confused after the next step 1-0.041= 0.959 0.041-0.068=0.027 after this I am confused what is the next…arrow_forward
- Suppose a survey of 899 college students who were asked about their smoking behavior. Of the students surveyed, 262 classified themselves as nonsmokers, but said "yes" when asked later in the survey if they smoked. These students were classified as "phantom smokers," meaning that they did not view themselves as smokers even though they do smoke at times. The authors were interested in using these data to determine if there is convincing evidence that more than 25% of college students fall into the phantom smoker category. Suppose that the sample of 899 college students can be regarded as representative of college students in the United States. (a) What hypotheses would you test to answer the question posed? H0: p = 0.25 versus Ha: p ≠ 0.25 H0: p ≠ 0.25 versus Ha: p = 0.25 H0: p = 0.25 versus Ha: p > 0.25 H0: p < 0.25 versus Ha: p > 0.25 H0: p = 0.25 versus Ha: p < 0.25 (b) Is the sample size large enough for a large-sample test for a population…arrow_forwardA study was recently conducted to assess the relationship between miscarriage and heavy alcohol use during the first trimester of pregnancy. Fifty women who suffered miscarriage were enrolled in the study along with 50 women who delivered full-term infants. Each participant’s use of alcohol during their first trimester of pregnancy was ascertained by face-to-face interview. For the purpose of this study, heavy alcohol use was defined as consuming four or more drinks on any one occasion during the first trimester of pregnancy. Study results found that a total of 18 women were heavy alcohol users, 14 among those who suffered a miscarriage. 1) What type of study design was used? Explain. 2) Set up the 2X2 contingency table for the data. 3) For this type of study design, what is the appropriate measure to describe the strength of the association between exposure and disease? 4) Calculate the measure identified in question 3. 5) Interpret the measure calculated in question 4. A recent study…arrow_forward20. Swearing is a common, almost reflexive, response to pain. Whether you knock shin into the edge your of a coffee table or smash your thumb with a ham- mer, most of us respond with a streak of obscenities. One question, however, is whether swearing has any effect on the amount of pain that you feel. To address this issue, Stephens, Atkins, and Kings- ton (2009) conducted an experiment comparing swearing with other responses to pain. In the study, participants were asked to place one hand in icy cold water for as long as they could bear the pain. Half of the participants were told to repeat their fa- vorite swear word over and over for as long as their hands were in the water. The other half repeated a neutral word. The researchers recorded how long each participant was able to tolerate the ice water.arrow_forward
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