If you have samples of n₁ = 22 and n₂ = 19, in performing the pooled-variance t test, how many degrees of freedom do you have? You have degrees of freedom.
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- 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 union of restaurant and foodservice workers would like to estimate this year's mean hourly wage, u, of foodservice workers in the U.S. Last year's mean hourly wage was $8.25, and there is reason to believe that this year's value is less than last year's. The union decides to do a statistical test to see if the value has indeed decreased. The union chooses a random sample of this year's wages, computes the mean of the sample to be $7.98, and computes the standard deviation of the sample to be $1.25. Based on this information, answer the questions below. What are the null hypothesis (H) and the alternative hypothesis (H,) that should be used for the test? |Ho: u is ? H: u is ? v|? ? In the context of this test, what is a Type I error? v the hypothesis that u is ? A Type I error is ? fact, u is ? v when, in Suppose that the union decides not to reject the null hypothesis. What sort of error might it be making? ?Two surfers and statistics students collected data on the number of days on which surfers surfed in the last month for 30 longboard (L) users and 30 shortboard (S) users. Treat these data as though they were from two independent random samples. Test the hypothesis that the mean days surfed for all longboarders is larger than the mean days surfed for all shortboarders (because longboards can go out in many different surfing conditions). Use a level of significance of 0.05. Longboard: 4,9,8,4,9,8,8,6,7,9,11,11,11,13,12,16,14,9,11,18,20,15,10,16,20,20,8,20,21,23 O Shortboard: 6,4,4,6,8,8,6,9,4,6,7,5,9,7,4,16,13,11,13,13,11,15,10,10,13,14,11,21,21,12 Determine the hypotheses for this test. Choose the correct answer below. O A. Ho: HL = Hs O B. Ho: HL = Hs OC. Ho: HL # Hs Ha: HL Hs O F. Ho: HL = Ps Ha: HL = Ps Ha: HL = Hs Ha: HL > Hs Find the test statistic for this test. t = (Round to two decimal places as needed.) Find the p-value for this test. p-value = (Round to three decimal places…
- In testing a certain kind or truck tire over rugged terrain, it is found that 40% of the trucks fail to complete the test run without a blowout. (a) Of the next 12 trucks tested, how many of them would you expect to have blowouts? (b) What is the variance of the number of blowouts experienced by the 12 trucks? What does that mean?An industrial psychologist feels that a big factor in job turnover among assembly line workers is the individual employee’s self-esteem. She thinks that workers who change jobs often (Population A) have, on the average, lower self-esteem, as measured by a standardized test, than workers whodo not (Population B). To determine whether she can support her belief with statistical analysis, she draws a simple random sample of employees from each population and gives each a test measuring self-esteem. The results are as follows: Group A 60 45 42 62 68 54 52 55 44 41 Group B 70 72 74 74 76 91 71 78 76 78 83 50 52 66 65 53 52 The psychologist believes that the relevant population scores are normally distributed, with equal, although unknown, variances. At the 0.1 level of significance, what should she concludeA union of restaurant and foodservice workers would like to estimate this year's mean hourly wage, u, of foodservice workers in the U.S. Last year's mean hourly wage was $8.08, and there is reason to believe that this year's value is different from last year's. The union decides to do a statistical test to see if the value has indeed changed. The union chooses a random sample of this year's wages, computes the mean of the sample to be $8.48, and computes the standard deviation of the sample to be $1.25. Based on this information, answer the questions below. What are the null hypothesis (H) and the alternative hypothesis (H,) that should be used for the test? H: u is [? |H: u is ? ? In the context of this test, what is a Type II error? A Type II error is ? v the hypothesis that u is ? when, in fact, u is ? Suppose that the union decides to reject the null hypothesis. What sort of error might it be making? ?
- Determine if the samples are independent or related. Two formulations of a new whitening soap are compared to their whitening effect. A random sample of 40 potential users of the soap is selected. Each person uses a randomization mechanism to determine which formulation is applied on the left arm so that the other formulation is applied on the right arm. After two weeks, they measured the effect of each formulation.Acne is a common skin disease that affects most adolescents and can continue into adulthood. A study compared the effectiveness of three acne treatments and a placebo, all in gel form, applied twice daily for 12 weeks. The study's 517 teenage volunteers were randomly assigned to one of the four treatments. Success was assessed as clear or almost clear skin at the end of the 12 week period. The results of the study can be seen in the table below. Using the appropriate statistical test, determine if there is significant evidence that the four treatments perform differently. If so, how do they compare.Use the following information to answer the question. A researcher wants to study different messaging platforms by collecting data on 40 individuals. Half of the individuals only use iMessage while the other half only use What's App. For the individuals who only used iMessage, they sent an average of 280 messages with a sample variance of 170 in the past week. For the individuals who only used What's App, they sent an average of 295 messages with a sample variance of 182 in the past week. Determine if there is a significant difference between the average messages sent between the two groups of individuals. Use a significance level of 1%. What is the null hypothesis? Group of answer choices A. The iMessage group on average sent more messages than the What's App group. B. The iMessage group on average sent less messages than the What's App group. C. There is no difference in the average number of messages sent between the two groups. D. There is a difference in the average…
- A hospital claims that 40% of its patients request a telephone. you are interested in disproving this claim. you select a random sample of 250 patients and find that 85% requested a telephone. what is the test statistic for this test?It has been found that 25.1% of men (Group 1) 20 years and older suffer from hypertension (high blood pressure) and 33.9% of women (Group 2) are hypertensive. A random sample of 164 of each gender was selected from recent hospital records, and the following results were obtained. Can you conclude that a higher percentage of women have high blood pressure? Use =0.05. Men: 42 patients had high blood pressure Women: 52 patients had high blood pressure Required: Test Value Only the final answer should be rounded-off to TWO decimal places.If you have samples of n1=19 and n2=24, in performing the pooled-variance t test, how many degrees of freedom do you have?
