The Institute of Psychiatry at Kings College London found that dealing with infomania (information overload) has a temporary, but significant derogatory effect on IQ.† Researchers divided volunteers into two groups. Eachsubject took an IQ test. One group had to check e-mail and respond to instant messages while taking the test, and the second group took the test without any distraction. The distracted group had an average score that was10 points lower than the average for the control group.Explain why it is important that the researchers created the two experimental groups in this study by using random assignment.O Without random assignment, the researchers cannot make multiple observations for each group.O Without random assignment, the researchers can't hold extraneous variables constant.O Using random assigment ensures the conclusion can be generalized to a larger population.O Using random assignment produces comparable, unbiased experimental groups.O Using random assigment allows the researchers to implement blocking for this experiment.

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Answered: test. One group had to check e-mail and…

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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Assume that matched pairs of data from a poll of Internet users who were asked if they make travel plans through the Internet result in 373 positive signs, 333 negative signs, and 22 ties when the value of the second variable is subtracted from the corresponding value of the first variable. Use the sign test with a 0.10 significance level to test the null hypothesis of no difference. Question content area bottom Part 1 Let η1 denote the median of the first variable and η2 denote the median of the second variable. What are the null and alternative hypotheses?
In this same passage, is it explanatory variable or response variable?
A poll was conducted to investigate opinions about global warming. The respondents who answered yes when asked if there is solid evidence that the earth is getting warmer were then asked to select a cause of global warming. The results are given in the accompanying data table. Use a 0.01 significance level to test the claim that the sex of the respondent is independent of the choice for the cause of global warming. Do men and women appear to agree, or is there a substantial difference? Human activity Natural patterns Don't know 307 Male 139 60 Female 327 158 59 Click here to view the chi-square distribution table. Identify the null and alternative hypotheses. Ho: The sex of the respondent and the choice for the cause of global warming are independent. The sex of the respondent and the choice for the cause of global warming are dependent. Compute the test statistic. (Round to three decimal places as needed.)
A researcher is studying the effects of his newly created lens on vision. He samples 9 people with poor vision and measures their visual distance (in feet) with the lens and then without the lens. Did people’s vision with the lens differ from their vision without? Participant # With Lens Without Lens 1 8 14 2 6 17 3 9 12 4 7 11 5 5 12 6 9 18 7 8 13 8 9 7 9 7 13 What kind of analysis will you use? Why? State the null and alternative hypothesis. Check your assumptions. Explain why each of them are or are not met. Sketch a distribution and shade the rejection region(s), including the corresponding critical value(s). Using R, calculate your test statistic and interpret the results of your test. (Don’t forget your 95% confidence interval and screenshots of your work!) What do you conclude about the null hypothesis? Are there significant differences?
Prof. Lopez wants to know whether type of the exam formats will impact on student’s final exam by ask a group of students taking the final exam with paper format and another group of students taking the same exam with computer format. a. Repeated measure t test b. One way ANOVA c. Independent- measures t test d. Correlation
An auditor for a local court system is tasked with comparing the rulings of two judges. The auditor needs to determine if Judge Hughes issues shorter sentences than Judge Wilson. The data below are the sentence lengths, in months, issued by each judge in their last twelve cases that dealt with operating a motor vehicle without a license. Test the claim that Judge Hughes issues shorter sentences than Judge Wilson for this particular type of case at the 0.05 level of significance. Let Judge Hughes' sentences be Population 1 and let Judge Wilson's sentences be Population 2. Assume that both populations are approximately normal and that the population variances are equal. Judge 24 12 12 30 Hughes 36 30 12 18 24 12 24 30 Judge 36 36 24 24 24 24 18 12 30 24 18 30 Wilson Copy Data Step 2 of 3: Compute the value of the test statistic. Round your answer to three decimal places.
Chi-sauare distribution table Question Viewer Degrees of Freedom 1 234569 7 8 10 0.995 0.010 0.072 0.207 0.412 0.676 0.989 1.344 1.735 2.156 0.99 0.020 0.115 0.297 0.554 0.872 1.239 1.646 2.088 2.558 Area to the Right of the critical value 0.975 0.001 0.051 0.216 0.484 0.831 1.237 1.690 2.180 2.700 3.247 0.95 0.004 0.103 0.352 0.711 1.145 1.635 2.167 2.733 3.325 3.940 I 0.90 0.016 0.211 0.584 1.064 1.610 2.204 2.833 3.490 4.168 4.865 0.10 2.706 4.605 6.251 7.779 9.236 10.645 12.017 13.362 14.684 15.987
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…
An auditor for a local court system is tasked with comparing the rulings of two judges. The auditor needs to determine if Judge Hughes issues shorter sentences than Judge Wilson. The data below are the sentence lengths, in months, issued by each judge in their last twelve cases that dealt with operating a motor vehicle without a license. Test the claim that Judge Hughes issues shorter sentences than Judge Wilson for this particular type of case at the 0.10 level of significance. Let Judge Hughes' sentences be Population 1 and let Judge Wilson's sentences be Population 2. Assume that both populations are approximately normal and that the population variances are equal. Judge Hughes 24 30 + Judge 18 18 36 30 Wilson 12 36 36 Copy Data Step 1 of 3: State the null and alternative hypotheses for the test. Fill in the blank below. Ho :μ₁ = 1₂ Ha: ₁ 12 24 M₂ 12 30 36 18 36 36 24 12
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?
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…
Is the proportion of wildfires caused by humans in the south higher than the proportion of wildfires caused by humans in the west? 380 of the 581 randomly selected wildfires looked at in the south were caused by humans while 318 of the 503 randomly selected wildfires looked at the west were caused by humans. What can be concluded at the a = 0.10 level of significance? a. For this study, we should use Select an answer b. The null and alternative hypotheses would be: Ho: Select an answer v Select an answer Select an answer v (please enter a decimal) Hj: Select an answer Select an answer vSelect an answer v (Please enter a decimal) c. The test statistic ? v (please show your answer to 3 decimal places.) d. The p-value = (Please show your answer to 4 decimal places.) e. The p-value is ? a f. Based on this, we should Select an answer g. Thus, the final conclusion is that ... |the null hypothesis. O The results are statistically significant at a = 0.10, so there is sufficient evidence to…

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