8.- Many studies have been conducted to test the effects of marijuana use on mental abilities. In onesuch study, groups of light and heavy users of marijuana in college were tested for memory recall, withthe summary results given below.MarijuanaLight UseHeavy UseMeanStandard Deviationni = 65n2 = 65X1 = 53.3X1 = 51.3S1 = 3.6S1 = 4.5a) Use a 0.01 significance level to test the claim that the population of heavy marijuana users has alower mean than the light users.Answer: Ho:Hạ:CV =RR =Test statistics =P-value =Conclusion: Keep H.Does the result of the hypothesis test suggest using marijuana be of concern to college students?Reject H.YESNOb) Construct a 98% confidence interval for the difference between the two population means.Answer:Based on the results, should there be a concern about using marijuana be of concern to collegestudents?YESNOHian hornital

Solution We will use t distribution to find CI.

Answered: 8.- Many studies have been conducted to…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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The leader of two postpartum women’s support groups is interested in the depression levels of the women in her groups. She administers the Center for Epidemiologic Studies Depression Scale (CES-D) screening test to the members of her groups. The CES-D is a 20-question self-test that measures depressive feelings and behaviors during the previous week. The mean depression level from the screening test for the 10 women in the first group is μ₁ = 16; the mean depression level for the 14 women in the second group is μ₂ = 10. Without calculating the weighted mean for the combined group, you know that the weighted mean is:
What type of statistical test is this? Is the test significant? In order to determine where the main mean differences lie, the researcher would also need to conduct a _______?
Researchers investigate how the presence of cell phones influence the quality of human interaction. Subjects are randomly selected from a population and divided into an experimental group that is asked to leave their phones in the front of the room and a control group that are not asked to leave their cell phones at the front of the room. Subjects are left alone for 10 minutes and then asked to take a survey designed to measure quality of interactions they had with others in the experiment. What statistical test is appropriate?
A Michigan study concerning preference for outdoor activities used a questionnaire with a six-point Likert-type response in which 1 designated "not important" and 6 designated "extremely important." A random sample of n1 = 44 adults were asked about fishing as an outdoor activity. The mean response was x1 = 4.9. Another random sample of n2 = 49 adults were asked about camping as an outdoor activity. For this group, the mean response was x2 = 4.1. From previous studies, it is known that ?1 = 1.5 and ?2 = 2.0. Does this indicate a difference (either way) regarding preference for camping versus preference for fishing as an outdoor activity? Use a 5% level of significance. Note: A Likert scale usually has to do with approval of or agreement with a statement in a questionnaire. For example, respondents are asked to indicate whether they "strongly agree," "agree," "disagree," or "strongly disagree" with the statement.
A psychologist wanted to study the effect of television violence on cortisol levels in the blood (high scores indicate high levels). The psychologist measured cortisol levels in seven participants before and after the participants watched a violent show. Participants' cortisol level scores are listed below. The researcher is interested if there is a change in the cortisol levels after watching the violent show. Carry out a t test for dependent means (using the .01 significance level). What should the researcher conclude? a.) Use the five steps of hypothesis testing. Label all the steps clearly. Show ALL work/calculations. b.) Report the statistic in APA format (the statistical sentence). Cortisol Levels in Blood Before and After Watching Violent Show Participant Before After A 3 3 B 15 3 9 6 D 6 8 E 8 F 4 1 Type here to search E I O KO 112 prt sc & * 6 E R T S G K V. alt alt 目 B.
2. A principal of high school was concerned with amount of time her students devote to working at after-school jobs. She randomly selected 25 students, obtained their working hours for 1 week and computed x = 12.5 hours and s = 4.5 hours. She claims that her students work significantly more than the mean of 10.7 hours from a study conducted by the National Association of State High School Association. Test her claim by using the 5% level of significance.
The drug Ritalin is designed to stimulate the central nervous system. In a random sample of 252 boys aged ten – twelve years old, it was found that 44 of the boys were taking Ritalin. It is known that the proportion of all boys aged 13 – 15 who take Ritalin is 24%. A researcher claims that the population proportions of boys who take Ritalin aged 10 – 12 is different than boys aged 13 – 15. Can you support this claim at the 5% significance level? a. Conduct a hypothesis test to test the claim at the 5% significance level. Be sure to state you Ho and Ha, your test statistic and p-value, whether or not you reject Ho and whether you support the claim. b. Show that you can use the large sample methodology. c. Write a complete sentence describing what a Type I error is in context.
A Michigan study concerning preference for outdoor activities used a questionnaire with a six-point Likert-type response in which 1 designated "not important" and 6 designated "extremely important." A random sample of n1 = 41 adults were asked about fishing as an outdoor activity. The mean response was x1 = 4.9. Another random sample of n2 = 50 adults were asked about camping as an outdoor activity. For this group, the mean response was x2 = 5.7. From previous studies, it is known that ?1 = 1.6 and ?2 = 1.5. Does this indicate a difference (either way) regarding preference for camping versus preference for fishing as an outdoor activity? Use a 5% level of significance.Note: A Likert scale usually has to do with approval of or agreement with a statement in a questionnaire. For example, respondents are asked to indicate whether they "strongly agree," "agree," "disagree," or "strongly disagree" with the statement. (a) What is the level of significance? .05 State the null and alternate…
What is the power of a study using a correlation, with a one-tailed test at the .05 significance level, in which the researchers predict a large effect size and there are 50 participants? How many participants do you need for 80% power in a planned study in which you predict a small effect size and will be using a correlation, one-tailed, at the .05 significance level?
any studies have been conducted to test the effects of marijuana use on mental abilities. In one such study, groups of light and heavy users of marijuana in college were tested for memory recall, with the results given below. Use a a 0.05 significance level to test the claim that in the population of heavy marijuana users, the mean number of items sorted correctly is lower than the mean number in the population of light users. Items sorted correctly by light marijuan users: n = 64, x overbar equals 53.5 , s = 3.6 Items sorted correctly by heavy marijuan users: n = 65, x overbar equals 51.3 , s = 4.5 a. Define the parameters A. p 1 equals The proportion of light marijuana users p 2 equals The proportion of heavy marijuana users B. mu 1 equals The mean number of light marijuana users mu 2 equals The mean number of heavy marijuan users C. p 1 equals The proportion of items sorted correctly by all light…

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