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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3. Dependent-samples t-test. A researcher wants to examine if play therapy can be an effective treatment for nightmares in children. Parents for a sample of 5-year-old children record each incident of a nightmare for 1 month before starting play therapy. After the start of play therapy, they continue to report each incident of a nightmare for another month. Do the data indicate a significant change in the number of nightmares? Test at the .05 level of significance Number of Nightmares 1 month during treatment 1 month before treatment 23 20 26 22 22 18 19 20 21 18 a. Conduct a complete hypothesis test b. Compute r? c. Give a full APA-style write up of your results
For a certain year, a study reports that the percentage of college students using credit cards was 87%. A college dean of student services feels that this is too high for her university, so she randomly selects 225 students and finds that 190 of them use credit cards. At the .01 significance level, is she correct about her university?
More Info Guilty Plea Not Guilty Plea Sent to Prison Not Sent to Prison 384 53 592 63 Print Done
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 _______?
A graduate student is interested in how viewing different types of scenes affects working memory. For his study, he selects a random sample of 36 adults. The subjects complete a series of working memory tests before and after walking in an urban setting. Before the walk, the mean score on the test of working memory was 9.1. After the walk, the mean score was 1.4 higher. The graduate student has no presupposed assumptions about how viewing different types of scenes affects working memory, so he formulates the null and alternative hypotheses as: H00 : μDD = 0 H11 : μDD ≠ 0 Assume that the data satisfy all of the required assumptions for a repeated-measures t test. The graduate student calculates the following statistics for his hypothesis test: Mean difference (MDD) 1.4 Estimated population standard deviation of the differences (s) 1.6 Estimated standard error of the mean differences (sMDMD) 0.2667 Degrees of freedom (df) 35 The t statistic 5.25 The critical values of t…
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?
Many people believe that criminals who plead guilty tend to get lighter sentences than those who are convicted in trials. The accompanying table summarizes randomly selected sample data for defendants in burglary cases. All of the subjects had prior prison sentences. Use a 0.05 significance level to test the claim that the sentence (sent to prison or not sent to prison) is independent of the plea. If you were an attorney defending a guilty defendant, would these results suggest that you should encourage a guilty plea? Guilty Plea Not Guilty Plea Sent to Prison 418 48 Not Sent to Prison 558 43
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.
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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