12. Does Weight Watchers work? Researchers randomly divided 500 people into two equal-sized groups. One group spent 6months on the Weight Watchers program. The other group received a pamphlet about controlling portion sizes. At theend of the study 35% of the subjects in the pamphlet group and 55% of the subjects in the Weight Watchers group hadlost at least 10 pounds. To test whether Weight Watchers is more effective for weight loss than pamphlets, a statisticianused an index card to represent each subject in the study and wrote whether or not the subject lost at least 10 pounds onthe index card. He then shuffled these cards together, and dealt them into two equal-sized groups. Which of the followingbest describes the expected result?The difference between the proportions of cards indicating whether or not the subject lost at least 10 pounds wil|be about 0.If Weight Watchers was effective, the difference between the proportions of cards indicating whether or not thesubject lost at least 10 pounds will be more than 20%.The difference between the proportions of cards indicating whether or not the subject lost at least 10 pounds willbe about 20%.

Here, an experiment is performed to determine whether weight watches is more effective for weight…

Answered: 12. Does Weight Watchers work?…

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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Dr. Mutombo would like to assess the impact of using an online statistics service to help students study for the PSY 215 departmental final exam. A sample of 12 students is obtained. Half (n = 6) are given access to the new stats online service while the other half (n = 6) serves as a control group. Each group of students is eventually tested on an exam out of a 100. Below is the data obtained: Answer the following questions. Show your work for full credit and round to the third decimal whenever necessary. Control Group Experimental Group M1=63 M2=88 SS1=1250 SS2=1750 a. State your hypotheses b. Does the data indicate a ɔignificant difference between the treatments for a two-tailed test at the .05 level of significance? Please specify (1) the t statistic, (2) specify the boundaries of the critical region, (3) state your decision. Show your computations for full credit c. Compute r2 d. Write up your results in a sentence as you would for a research paper; use APA format.
A researcher is testing the effect of one independent variable using three treatment conditions. She compares three group means where there are different people in each group. It is best for her to use which type of statistical analysis?
A substance abuse counselor wants to demonstrate the effect of situational stress on alcohol cravings. He recruits two groups of men who are similar in respect to history of alcohol use and demographic variables. He divides them in to two groups. In one group(n=11), the men are exposed to a stressful situation and then asked to complete a measure rating their alcohol cravings on a scale from 0-10, where 0 representsno cravings and 10 represents intense cravings. In the second group (n=10), the men are exposed to a neutral situation and asked to complete the same measure. What test and graph should I create to find out if a stressful situation result in more intense alcohol cravings than a non-stressful situation?
Suppose you work as a manager for a large clothing store. You are considering introducing a loyalty program to encourage customers to spend more at your store. Before rolling out your program to the public, you want to do a small experiment to estimate its effectiveness. You offer the loyalty program to 10 random customers, and also observed the sales of 27 random customers who did not get the program as a control group. The customers that were part of the loyalty program had average monthly sales of $302.57 and a sample standard deviation of $49.73. For the control group, the customers had an average monthly sales of $231.65 and a sample standard deviation of $67.88. * Given a 95% confidence interval critical value of t = 2.04, what is the upper bound (upper end) of a 95% confidence interval for the difference between two averages? Use (μloyalty program no loyalty program) for the order. Note: 1- Only round your final answer. Round your final answer to two decimal places.
1. Imagine you work for a psychological testing agency and you have been assigned the role of analysing the data. The experiment involves testing 4 different drugs in treating 20 asthma patients. They were each asked to take the 4 different drugs in 4 weeks and record how many attacks they had while taking each drug per week. a. Explain why this is a repeated measures design? b. Explain two reasons why this design is the best choice?
The Bureau of Labor Statistics reports that the official unemployment rate for Black people was 10.4% and 4.7% for White people in February 2015. Select all correct answers for this question. O The samples of white and black people are independent. The explanatory variable is the unemployment rate. The response variable is the unemployment rate. The response variable is race.
Security scans are often completed on computers in a particular college to assess the security risk from viruses etc. A sample of 120 computers which are considered at risk for viruses and other security issues are checked with a particular security scanner on a Monday and then monitored over the following week. The number of computers which broke down over the following week were recorded. The results are as follows: Security Scan (% Risk) Breakdown No Breakdown Low Risk (0 - 10%) 3 61 Slight/Moderate Risk (10 – 30%) 13 28 High Risk (>30%) 12 3 (i) Based on the above sample work out the probability that a computer in the college will breakdown. Input your answer correct to 4 decimal places here: (ii) Based on the above sample work out the probability that a computer has a low risk level OR doesn't breakdown. Input your answer correct to 4 decimal places here: (iii) Based on the above sample work out the probability that a computer has a high risk AND has a breakdown. Input your answer…
Thirty-five percent of all Americans drink bottled water more than once a week (Natural resources Defense Council, December 4, 2015). Suppose you have been hired by the Natural Resources Defence Council to investigate bottled water consumption in St. Paul. You plan to select a sample of St. Paulites to estimate the proportion who drink bottled water more than once a week. Assume the popluation proportion of St. Paulites who drink bottled water more than once a week is 0.35 , the same as the overall proportion of Americans who drink bottled water more than once a week. Suppose you select a sample of 540 St. Paulites. Show the sampling distribution of “p with a line over it” (to 4 decimals). E(p with a line over it) = 0` p with a line over it = Based upon a sample of 540 St. Paulites, what is the probability that the sample proportion will be within 0.08 of the population proportion (to 4 decimals). Probability = Suppose you select a sample of 190 St. Paulites. Show the sampling…
The IRS is concerned with improving the accuracy of tax information given by its representatives over the telephone. Previous studies involved asking a set of 25 questions of a large number of IRS telephone representatives to determine the proportion of correct responses. Historically, the average proportion of correct responses has been 72 percent. Recently, IRS representatives have been receiving more training. On April 26, the set of 25 tax questions were again asked of 20 randomly selected IRS telephone representatives. The proportions of correct answers were: 21, 20, 19, 16, 22, 15, 21, 15, 17, 15, 24, 17, 24, 21, 18, 16, 23, 16, 21, and 20. a. What are the upper and lower control limits for the appropriate p-chart for the IRS? Use z = 3. The UCL, equals and the LCLp equals ☐ . (Enter your responses rounded to four decimal places. If your answer for LCLp is negative, enter this value as 0.)
Caden then performs a significance test. First, he performs 100 simulations. For each simulation, he randomly reorganizes the subjects into two groups, A and B, of size 10. In the simulations, group A plays the role of the treatment group and group B plays the role of the control group. After each simulation, he subtracts the average for group B from the average for group A. The distribution of the differences for all 100 simulations is shown in the histogram. 30 28 26 24 22 12 10 6. 2 Group A avg. - Group B avg. In the original experiment, the average for the treatment group was 0.8 higher than the average for the control group. Based on the 100 simulations, are the results of the experiment significant at the 5% level? yes no Number of simulations [-2.7, -2.2) [-2.2, -1.7) [-1.7, -1.2) [-1.2, -0.7) [-0.7, -0.2) [-0.2, 0.3) [0.3, 0.8) [0.8, 1.3) [1.3, 1.8) [1.8, 2.3) [2.3, 2.8)
How is the study condition within subjects design?
A study compared the felt intensity of unrequited love among three groups - individuals who were currently experiencing unrequited love, those who had previously experienced unrequited love and described their experiences retrospectively, and those who had never experienced unrequited love but described how they thought they would feel if they were to experience it. The results of the study are summarized in the accompanying table. Determine the significance of the difference among groups, using the 5% level. N 40 40 40 M 3.5 3.3 3.7 S2 5.3 5.8 4.8 1. What is th null hyp? 2.The comparison distribution will be an F distribution with df= ? and df=? 3.Determine the cutoff sample score on the comparison distribution at which the null hypothesis should be rejected for the data. At 0.05 the cutoff for F=? 4. Determine the sample's score on the comparison distribution for the data. F=?

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