A researcher randomly assigns college freshmen to either of two experimental conditions. Because both groups consist of college freshmen, someone claims that it is appropriate to use a t test for the two related samples. Comments?

A researcher randomly assigns college freshmen to either of two experimental conditions. Because both groups consist of college freshmen, someone claims that it is appropriate to use a t test for the two related samples. Comments?

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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which of the following study is appropiate for the one sample t test?
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. 4 6 9 4 7 4 4 6 8 7 7 8 10 8 6 10 7 4 10 7 13 9 12 5 11 10 15 7 12 4 15 15 12 11 11 11 11 11 19 11 18 10 15 13 10 11 17 12 18 14 21 16 9 9 23 22 22 22 21 10 Find the test statistic for this test. t= (Round to two decimal places as needed.) Find the p-value for this test. p= (Round to three decimal places as needed.) What is the conclusion for this test?
Before the semester began, Professor Keithley predicted that 15% of hisphilosophy students would receive an A, 30% a B, 40% a C, 10% a D, and 5%an F. At the end of the semester, 14 of Professor Keithley’s philosophy studentsearned an A, 19 a B, 12 a C, 5 a D, and 2 an F.Use the Chi-Square test and a 0.05 level of significance to determine if ProfessorKeithley’s predicted percentages were accurate. (State your null and alternativehypothesis, find the critical values and test statistics, make a decision, and writea conclusion based on your results).
Researchers studying starfish collected two independent random samples of 40 starfish. One sample came from an ocean area in the north, and the other sample came from an ocean area in the south. Of the 40 starfish from the north, 6 were found to be over 8 inches in length. Of the 40 starfish from the south, 11 were found to be over 8 inches in length. Which of the following is the test statistic for the appropriate test to investigate whether there is a difference in proportion of starfish over 8 inches in length in the two ocean areas (north minus south) ? 6−11640+1140√ A 6−110.1540+0.27540√ B 0.15−0.275(0.15)(0.275)(140+140)√ C 0.15−0.275(0.2125)(0.7875)(140+140)√ D 0.15−0.275(0.2125)(0.7875)140+140√
In a study, a large sample representative of the households in the US were asked about their smoking habits. The data suggested that current smokers were on average much healthier than those who recently stopped smoking. Investigators concluded that smoking does not necessarily lead to worse health outcomes. Consider the following statements. Select the ones you agree with, based on the information given. Group of answer choices A.In a randomized experiment, smoker and non-smoker groups are similar across all potential characteristics. b.The conclusions were justified by the data. c.This is an observational study. d.This study is a randomized controlled experiment. e.The results can be explained due to confounding. Current smokers are different from those who recently stopped in ways that are related to health outcomes.
Since first year students reported at the University of Nairobi, a shop attendant at students hall of residence has noticed an increase in sales of fanta soda. As a statistician and market analyst, you would wish to know if there is relationship between soda preference and year level of study at the University of Nairobi. A random sample of 200 students was taken. Their year level and soda preference are given in the table. Soda/Year of study Fist Year Second Year Соса cola 33 57 Fanta 30 20 Spirit 5 35 Stoney 12 8 Based on this information, obtained the Chi-square calculated in 2 decimal places
Homser Lake, Oregon, has an Atlantic salmon catch-and-release program that has been very successful. The average fisherman's catch has been ? = 9.0 Atlantic salmon per day. Suppose that a new quota system restricting the number of fishermen has been put into effect this season. A random sample of fishermen gave the following catches per day:12 6 11 12 5 0 27 8 7 6 3 12 12 I need help with (b) and the value of the sample test statistic
2. We ask whether people will score higher or lower on a questionnaire of their well-being when they are exposed to sunshine compared to when they're not exposed to sunshine. A sample of 8 people is first measured after low levels of sunshine exposure and then again after high levels of exposure. We get the following pairs of scores: Low: 14 13 17 15 18 17 14 16 High: 18 12 20 19 22 19 19 16 a. State the null and alternative hypotheses. b. Using an alpha = 0.05, what is t (crit)? c. Using SPSS, calculate t (obu) (Use paired/related sample t test to obtain this info) d. What should you conclude?
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: 4,8,8,4,7,7,10,6,8,10,12,11,9,15,11,16,12,9,12,18,19,15,11,15,19,20,9,23,21,23 Shortboard: 6,4,4,6,7,7,8,9,4,7,8,5,9,7,4,15,11,10,13,12,11,14,9,11,12,16,9,20,22,11 Determine the hypotheses for this test. Choose the correct answer below. O A. Ho: PL=Ps O B. Ho: HL Hs O F. Ho: HL> Hs 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 as needed.) What is the conclusion for this…
A university wanted to see whether there was a significant difference in age between its day staff and evening staff. A random sample of 35 staff members is selected from each group. The data are given below. Test the hypothesis that there is no difference in age between the two groups. Use a =0.05. Day Staff 22 24 24 23 19 19 23 22 18 21 21 18 18 25 29 24 23 22 22 21 20 20 20 27 17 19 18 21 20 23 26 30 25 21 25 Evening Staff 18 23 25 23 21 21 23 24 27 31 24 20 20 23 19 25 24 27 23 20 20 21 25 24 23 28 20 19 23 24 20 27 21 29 30
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 warehouse manager wants to know if there is an association between the shift worked and being on time for work. To investigate, he selects a random sample of 70 workers and classifies each one according to the shift they worked most recently and whether they were on time for work. He was unable to classify a substantial number of people as being on time, so he classified those individuals as unknown. The data are displayed in the table. The manager would like to know if these data provide convincing evidence of an association between the shift worked and being on time in the large population of all workers at this warehouse. The random and 10% conditions are met. Is the Large Counts condition met? Yes, the smallest expected count is 5, so all expected counts are at least 5. Yes, the smallest expected count is 8.54, so all expected counts are at least 5. No, the smallest expected count is 2.56, so the expected counts are not all at least 5. No, the smallest expected count is…