10. A researcher states that the survival time of an organism is negatively related to the amount of a specific pollutant present in the ecosystem. This means that above-average amounts of pollutant tend to accompany below-average survival times. below-average amounts of pollutant tend to accompany below-average survival times. below-average amounts of pollutant can be accompanied by either above- or below-average survival times. above-average amounts of pollutant tend to accompany above-average survival times.
11. Here is the protease activity found in walnuts preserved in buffers of varying pHs: pH 4.5 5 6 7 8 9 10 protease activity 0.17 0.245 0.28 0.055 0.02 0 0.025 Which of the following scatterplots is a correct representation of the data? 12. Below is a scatterplot of heights (in centimeters) of Spartina alterniflora plants against the amount of sunlight they were given (in minutes). Those plants grown at sea level are represented by a closed circle and those grown on the ISS are shown with an open circle. We conclude that there is a weak association for both locations. association can’t be assessed here since a categorical variable is involved. there is a strong positive association for sea level plants, but a negative association for ISS plants. there is a strong association for sea level plants, but a positive association for ISS plants.
13. Tail-feather length in birds is sometimes a sexually dimorphic trait. That is, the trait differs substantially for males and for females. Researchers studied the relationship between weight (x) and tail-feather length (y) in a sample of five wild male long-tailed finches. Here are the data: The value of the linear correlation coefficient between weight and tail feather length is approximately 0.942. 0.888. 0.789. We should not be computing this value because the relationship is not linear.
14. Tail-feather length in birds is sometimes a sexually dimorphic trait. That is, the trait differs substantially for males and for females. Researchers studied the relationship between tail-feather length (measuring the R1 central tail feather) and weight in a sample of 20 male and 21 female long-tailed finches raised in an aviary. Which of the following statements is NOT true? Overall, females tend to have smaller tail feathers than males, for a given body weight. Both males and females show a clear positive linear relationship between weight and tail-feather length. Male birds that are heavier tend to have longer tail feathers. There appears to be no relationship between body weight and tail-feather length in female birds. 15. Suppose we fit the least-squares regression line to a set of data. Points with unusually large values of the residuals are called outliers. response variables. correlated. the slope. 16. John’s parents recorded his height at various ages up to 66 months. Below is a record of the results. John’s parents decide to use the least-squares regression line of John’s height on age based on the data in the previous problem to predict his height at age 21 years. We conclude that John’s height, in inches, should be about half his age, in months. the parents will get a fairly accurate estimate of his height at age 21 years because the data are clearly correlated. such a prediction could be misleading because it involves extrapolation. All of the above 17. A researcher noticed that, for streams along the east coast, the amount of money spent on restoration and the number of distinct fish populations present appeared to have a negative correlation. To investigate this, the researcher should begin his research by using the least-squares regression line. a well-designed experiment. the correlation coefficient. the square of the correlation coefficient. 18. Tail-feather length in birds is sometimes a sexually dimorphic trait. That is, the trait differs substantially for males and for females. Researchers studied the relationship between weight (x) and tail-feather length (y) in a sample of five wild, male long-tailed finches. Here are the data: The value of the y intercept for the least-squares regression line is 25.547 mm. 25.547 mm/g. 2.815 mm/g. 2.815 g/mm. 19. At a local health club, a researcher samples 75 people whose primary exercise is cardiovascular and 75 people whose primary exercise is strength training. The researcher’s objective is to assess the effect of type of exercise on cholesterol. Each subject reported to a clinic to have his or her cholesterol measured. The subjects were unaware of the purpose of the study, and the technician measuring the cholesterol was not aware of the subject’s type of exercise. This is a(n) double-blind experiment. observational study. experiment, but not a double-blind experiment. matched pairs experiment. 20. The city council in a suburb of Raleigh is interested in the level of public support for a tax increase to support restoration of nearby parks and waterways. A marketing research firm is selected that then selects a simple random sample of 50 adult residents and contacts each to determine whether the resident would be opposed to the tax increase. Of these, 15 indicated that they would be opposed. The sample is the 50 residents selected. the 15 residents not in favor of the increase. all residents in the suburb. the 35 residents in favor of the increase. 21. A student organization at a local college posted a poll on its website. After a semester, the results were tallied and it was found that 95% of the respondents were in favor of raising fees to increase funding for student organizations. This conclusion was based on data collected from 5000 votes cast on the website. Based on the IP addresses of the respondents, it was later determined that 3200 of the votes were cast from a single off-campus computer belonging to a member of the student organization that posted the poll. The results of this poll are probably biased, but only slightly since the sample size was quite large. reliable since there were still 1800 other randomly obtained respondents. biased, overstating the popularity of raising fees. biased, understating the popularity of raising fees. 22. An SRS of 1200 adult Americans is selected, and each person is asked the following question. “In light of the huge national deficit, should the government at this time spend additional money to establish a national system of health insurance? Only 39% of those responding answered “yes.” This survey probably overstates the percent of people that favor a system of national health insurance. is very inaccurate, but neither understates nor overstates the percent of people that favor a system of national health insurance. Since simple random sampling was used, it is unbiased. is reasonably accurate since it used a large, simple random sample. probably understates the percent of people that favor a system of national health insurance.