In Exercises 5–20, assume that the two samples are independent simple random samples selected from
20. Blanking Out on Tests Many students have had the unpleasant experience of panicking on a test because the first question was exceptionally difficult. The arrangement of test items was studied for its effect on anxiety. The following scores are measures of “debilitating test anxiety.” which most of us call panic or blanking out (based on data from “Item Arrangement, Cognitive Entry Characteristics. Sex and Test Anxiety as Predictors of Achievement in Examination Performance,” by Klimko, Journal of Experimental Education, Vol. 52, No. 4.) Is there sufficient evidence to support the claim that the two populations of scores have different means? Is there sufficient evidence to support the claim that the arrangement of the test items has an effect on the score? Is the conclusion affected by whether the significance level is 0.05 or 0.01?
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ESSENTIALS OF STATISTICS 6TH ED W/MYSTA
- Refer to the data presented in Exercise 2.86. Note that there were 50% more accidents in the 25 to less than 30 age group than in the 20 to less than 25 age group. Does this suggest that the older group of drivers in this city is more accident- prone than the younger group? What other explanation might account for the difference in accident rates?arrow_forward2. Let X - tp. Verify the mean and variance formulas. (Hint: Let X = p/2UV-1/2.)arrow_forwardPart 4 of 4 Summarize the results. There (Choose one) enough evidence to conclude that the second-graders in the superintendent's school district have h the nationwide average. differe is is notarrow_forward
- Untitled Section 21- Which of the following statements is true? * a. When the variance of the OLS estimator increases, the standard error decreases, and the t-statistic increases b. When the variance of the OLS estimator increases, the standard error increases, and the t-statistic decreases C. When the variance of the OLS estimator inereases, the standard error increases, and the t-statistc increases d. When the variance of the OLS estimator decreases, the standard error decreases. and the t-statistic decreasesarrow_forwardA random variable X has only two values a and b with P(X = a) = p , P(X = b) = q (p + q = 1).Find its mean value and variation.arrow_forwardA population has SS- 100 and variance, o-4. What is the value of x- jal for the population? O 100 O 400 O 25arrow_forward
- The table below lists leading digits of 317 inter-arrival Internet traffic times for a hospital computer along with the frequencies of leading digits expected with Benford’s Law. (Benford’s Law is an observation about the leading digits of the numbers found in real-world data sets. We would think that each digit would occur about 11.1% of the time, but that is not how it works. It has been used to detect fraud.) LeadingDigit1 2 3 4 5 6 7 8 9 Occurrence 76 62 29 33 19 27 28 21 22 Benford’sLaw 30.1% 17.6% 12.5% 9.7% 7.9% 6.7% 5.8% 5.1% 4.6% Test to see if the leading digits in the Internet Traffic times occur at the same frequency as given by Benford’s Law.arrow_forwardExercise 4. Suppose that X is a random variable with mean 10 and standard deviation 4. Also suppose that Y is a random variable with mean 20 and standard deviation 5. The correlation between X and Y is p = 0.6. Calculate the mean and standard deviation of the random variable Z for each of the following cases. (a) Z = 3Y (b) Z = Y-Xarrow_forwardIn a previous practice assignment, you learned about a study in which volunteers (who were all around 30 years of age) from the Chicago area wore light sensors to measure their exposure to sunshine. It was found that those who experienced more daylight had lower body mass indexes (BMIs). The study was observational. It was not an experiment, so conclusions about cause and effect could not be made. Let's redesign the observational study described above into an experimental study.arrow_forward
- A researcher wants to find the effect of a special diet on systolic blood pressure. A sample of 7 adults was selected to start them on this diet for 3 months. Based on this information, can it be stated that systolic blood pressure changes with the special diet? The test statistic that will determine whether systolic blood pressure changes with the special diet is...... A. 1.23 B. 0.48 C. 18.1 D. 21.08 E. 4.08arrow_forwardplease, answer the 3 questionsarrow_forwardPart C and Darrow_forward
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