Concept explainers
An article reported the results of a peer tutoring program to help children learn to read. In the experiment, the children were randomly divided into two groups: the experimental group received peer tutoring along with regular instruction, and the control group received regular instruction with no peer tutoring. There were n1 = n2 = 30 children in each group. The Gates-MacGintie Reading Test was given to both groups before instruction began. For the experimental group, the mean score on the vocabulary portion of the test was x1 = 344.5, with sample standard deviation s1 = 49.5. For the control group, the mean score on the same test was x2 = 353.8, with sample standard deviation s2 = 50.9. Use a 5% level of significance to test the hypothesis that there was no difference in the vocabulary scores of the two groups before the instruction began.
What is the value of the sample test statistic? (Test the difference μ1 − μ2. Round your answer to three decimal places.)
Trending nowThis is a popular solution!
Step by stepSolved in 2 steps
- Emma's On-the-Go, a large convenience store, has to decide where in the store to put its magazine rack. The manager at Emma's experiments with a selection of different locations, choosing a sample of days at each location. Each day, the manager records the amount of money brought in from the sale of magazines. It's possible to test whether there is a difference in the mean daily sales for the different locations by doing a one-way, independent-samples ANOVA test. The variable of interest is the daily sales, in dollars, from magazines at Emma's. In the ANOVA test, the "groups" are the different locations, and the "samples" are the daily magazine sales actually examined by the manager. (a) The following ANOVA table gives a summary of such an ANOVA test. Fill in the missing cell in the table (rounded to two decimal places). Degrees of freedom Source of Sum of Mean square F statistic variation squares Treatments (between groups) 4 3209.01 802.25 Error 215 94,380.7 438.98 (within groups)…arrow_forwardA professor wants to know which type of instructional mode students had more satisfaction. The professor randomly selected n = 5 students from each of the following types of classes: online only, hybrid, and face-to face only. Student were given a satisfaction survey. Are their differences in student satisfaction among the different instructional modes. The data are below: Online Hybrid Face-to-Face 3 3 4 3 3 1 3 1 3 2 2 2 2 1 3 Calculate the Tukey HSDarrow_forwardWhat is the variable of interest? Whether or not a patient is satisfied with the level of care. Whether or not all the patients like the doctor. The sample proportion of patients satisfied with the service Whether or not a patient likes the doctor. The number of patients that are satisfied with the servisearrow_forward
- Using the same anti-venom study, answer the following questions. A study was done on children (6 months to 18 years of age) who had (nonlethal) scorpion stings. Researchers wanted to know the effectiveness of a new anti-venonm. Each child was randomly assigned to receive a shot of the anti-venom or a placebo shot. Researchers recorded whether or not their condition improved over the next four hours. a. Identify the population for the study. b. Identify the sample for the study. (HINT: See #1) c. Was this an observational study or a controlled experiment? Explain how you know. d. Assuming the rest of the study was well-designed, use your answers to discuss whether it would be reasonable to conclude that the new anti-venom is effective at treating nonlethal scorpion stings in children. For the toolbar, press ALT+F10 (PC) or ALT+FN+F10 (Mac). TTTTParagraph Arial 3 (12pt) 三,三,T. 回i:公 E=E= = T T, U HTML CSS O Mashupsarrow_forwardA researcher is examining whether two variables, A and B, are independent or not. Variables A and B have 5 and 6 categories, respectively. A sample of n = 400 subjects is obtained. What is the degrees of freedom in the chi-squared test?arrow_forwardIn a One-way Between Subject ANOVA, the number of levels the IV had was 3, and the within/error degrees of freedom was 48. What was the total number of people in the participants analyzed in the studyarrow_forward
- Use the three-read strategy to understand the following exercise from a statistics textbook, and then proceed to complete the exercise. Suppose that in a study to determine if hormone therapy increases risk of venous thrombosis in menopausal women, each person in a sample of 589 women who had been diagnosed with venous thrombosis was classified according to hormone use. Each woman in a sample of 2,243 women who had not been diagnosed with venous thrombosis was also classified according to hormone use. Data from the study are given in the accompanying table. The women in each of the two samples were selected at random from patients at a large HMO in a certain U.S. state. Current Hormone Use None EsterifiedEstrogen ConjugatedEquineEstrogen Venous Thrombosis 382 86 121 No VenousThrombosis 1,439 505 299 Is there convincing evidence that the proportions of those who would fall into each of the hormone use categories are not the same for women who have been diagnosed with…arrow_forwardWhich statistical test should be used? Researchers wondered if frequent checking of email increases stress. They randomly assigned their participants to check email just three times a day for a week, and then in the second week, to check email as often as they wanted. The researchers did find that participants were less stressed, on average, during the limited email week than during the unlimited email week. Which statistical test should be used? A professor was interested in studying how academic major (Psychology vs. Chemistry) is related to creativity (assessed by a creativity questionnaire). Which statistical test should be used to for a difference between psychology and chemistry majors in creativity?arrow_forwardSuppose 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.arrow_forward
- 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.arrow_forwardA 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…arrow_forwardA 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.arrow_forward
- MATLAB: An Introduction with ApplicationsStatisticsISBN:9781119256830Author:Amos GilatPublisher:John Wiley & Sons IncProbability and Statistics for Engineering and th...StatisticsISBN:9781305251809Author:Jay L. DevorePublisher:Cengage LearningStatistics for The Behavioral Sciences (MindTap C...StatisticsISBN:9781305504912Author:Frederick J Gravetter, Larry B. WallnauPublisher:Cengage Learning
- Elementary Statistics: Picturing the World (7th E...StatisticsISBN:9780134683416Author:Ron Larson, Betsy FarberPublisher:PEARSONThe Basic Practice of StatisticsStatisticsISBN:9781319042578Author:David S. Moore, William I. Notz, Michael A. FlignerPublisher:W. H. FreemanIntroduction to the Practice of StatisticsStatisticsISBN:9781319013387Author:David S. Moore, George P. McCabe, Bruce A. CraigPublisher:W. H. Freeman