Concept explainers
Does It Make Sense? For Exercises 5–8, determine whether the statement makes sense (or is clearly true) or does not make sense (or is clearly false). Explain clearly; not all of these statements have definitive answers, so your explanation is more important than your chosen answer.
7. Smoking and Cotinine. Data showed a strong
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Statistical Reasoning for Everyday Life (5th Edition)
- A researcher believes that the so-called “sugar high” is not real. He gathered 30 adolescents and recorded their activity level in the scale of 0 – 100 (0 = not active and 100 = super active). First, he recorded participants’ activity level before they consumed candy. After recording their pre-sugar activity level, the researcher gave out 5 Snickers bars to participants. Then, he recorded their post-sugar activity level. The average difference between post-sugar and pre-sugar activity level is 50 (i.e., the activity levels are higher after sugar than prior to it) with a standard deviation of 10. A). Complete test statistic and critical values B). Conclusionarrow_forwardThe results of a recent study show that the proportion of people in the western United States who use seat belts when riding in a car or truckis under 84%. You want to support this claim.arrow_forwardPls solve part darrow_forward
- A researcher tests whether cocaine use increases impulsive behavior, which is measured as the number of impulsive events per hour. The researcher gives either 0 ng, 10 ng, 15 ng, or 20 ng to each group of mice. 1. What is the independent and dependent variable?arrow_forwardLevene's test tests whetherarrow_forwardA certain affects virus 0.4% of the population (in a population of 100,000 people, 400 will be infected with the virus). A test used to detect the virus in a person is positive 87% of the time if the person has the virus (true positive) and it is positive 14% of the time if the person does not have the virus (false positive). Fill in the remainder of the following table and use it to answer the questions below. Infected Not Infected Total Positive Test Negative Test Total 400 99,600 100,000arrow_forward
- A certain affects virus 0.4% of the population (in a population of 100,000 people, 400 will be infected with the virus). A test used to detect the virus in a person is positive 87% of the time if the person has the virus (true positive) and it is positive 14% of the time if the person does not have the virus (false positive). Fill in the remainder of the following table and use it to answer the questions below. Infected Not Infected Total Positive Test Negative Test Total 400 99,600 100,000 Round all percents to the nearest tenth of a percent as needed. a) Examine the "Positive Test" row of the table. If a person tests positive for the virus, what is the probability that the person is really infected. (Note: in medical terminology, this probability measures the "positive predictive value" of the test) b) If a person tests negative for the virus, what is the probability that the person really is not infected. (This is called the "negative predictive value")arrow_forwardThe first test a doctor would order to determine whether a person is infected with HIV (the virus that causes AIDS) is the ELISA test. It detects antibodies and antigens for HIV. A study in Statistical Science by J. Gastwirth estimated that, if the person is actually infected with HIV, this test produces a positive result 97.7% of the time. If a person is not infected with HIV, the test result is negative 92.6% of the time. According the the US Centers for Disease Control (CDC), an estimated 1.1 million Americans out of a population of 321 million were infected with HIV in 2015. Using the information above, determine the probability that a randomly selected person whose ELISA test is positive actually is infected with HIV? a. What is the probability that a randomly selected American is infected with HIV? b. Using the answer to part (a) and the conditional probabilities of positive and negative ELISA test results, fill out the contingency table below: ELISA Test Result…arrow_forwardA poll summarized the results of a survey of 2,400 adults and 500 teens aged 13 to 17. It was reported that 32% of the teens surveyed and 39% of the adults surveyed indicated that they believe in reincarnation. The samples were selected to be representative of American adults and teens. n USE SALT Use the data from this survey to estimate the difference in the proportion of adults who believe in reincarnation and the proportion of teens who believe in reincarnation by calculating a 95% confidence interval for the difference. (Use padults - peens: Round your answers to three decimal places.) to Interpret your interval in context. O There is a 95% chance that the true difference between the proportion of adults who believe in reincarnation and the proportion of teens who believe in reincarnation is in the interval. Because both endpoints of the confidence interval are positive, we believe that the proportion of adults who believe in reincarnation is less than the proportion of teens aged…arrow_forward
- A Superintendent of Education wants to determine if test scores are independent of school location. The following table shows the number of students achieving a basic level in the following subjects. Test the claim at a = 0.01 that location of school and academic achievement are independent. Location of School Subject Reading Math Science Urban 43 42 38 Suburban 63 66 65arrow_forwardbartam 40. GUeTticient of skewness and interpret the result : Age below (yrs) No. of employees 25 8. 30 20 35 40 40 65 45 80 50 92 55 100arrow_forwardThe mode score on a statistics exam was 83. Which of these interpretations is correct? A.More students received an 83 than any other score. B.80 is the highest score in the class. C.No one scored below 50. D.A score of 83 was slightly below average.arrow_forward
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