Preliminary data analyses indicate that applying the z-test (Procedure 9.1 on page 388) in Exercises 9.83–9.88 is reasonable.
9.88 Worker Fatigue. A study by M. Chen et al. titled “Heal Stress Evaluation and Worker Fatigue in a Steel Plant” (American Industrial Hygiene Association, Vol. 64, pp. 352-359) assessed fatigue in steel-plant workers due to heat stress. A random sample of 29 casting workers had a
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Introductory Statistics (10th Edition)
- Researchers have noted a decline in cognitive functioning as people age (Bartus, 1990). However, the results from other research suggest that the antioxidants in foods such as blueberries may reduce and even reverse these age-related declines (Joseph et al., 1999). To examine this phenomenon, suppose that a researcher obtains a sample of n = 16 adults who are between the ages of 65 and 75. The researcher uses a standardized test to measure cognitive performance for each individual. The participants then begin a 2-month program in which they receive daily doses of a blueberry supplement. At the end of the 2-month period, the researcher again measures cognitive performance for each participant. The results show an average increase in performance of MD = 7.4 with SS = 1215. Does this result support the conclusion that the antioxidant supplement has a significant effect on cognitive performance? Use a two-tailed test with α = .05. Show your computations.arrow_forwardRhino viruses typically cause common colds. In a test of the effoctivoness of echinecea, 32 of the 39 subjects treated with echinacea developed ithinavirus infections In a placebo group, 90 of the 107 subjects developed thinovirus infections Use a 0.05 significance level to test the clam that echinacea has an effect on thinovinus infections Complete parts (a) through (c) below COO a. Test the claim using a hypothesis test Consider the first sample to be the sample of subjects treated with echinacea and the second samplo to be the sample of subjects troated with a placebo What are the null and alternative hypotheses for the hypothesis test? OA Ho P P2 H P P2 OB. Ho P P2 H P, P2 H, P Pa VE Ho Pr"P2 Hy P,P OF M PPa H, P P |OD. Ho P1 P2 H, P P2 Identify the test statistic (Round to two decimal places as noeded)arrow_forwardA data set from a study that examined the effect of a specific diet on blood pressure is provided . Participants (n = 72) were randomly assigned either to a group that was put on the diet (Diet = Present) or to a group that was not put on the diet (Diet = Absent), and researchers wanted to know whether the diet had a significant impact on blood pressure. Fully interpret the results in the context of this study (i.e., report the conclusions as related to the research question).arrow_forward
- Researchers have noted a decline in cognitive functioning as people age (Bartus, 1990). However, the results from other research suggest that the antioxidants in foods such as blueberries may reduce and even reverse these age-related declines (Joseph et al., 1999). To examine this phenomenon, suppose that a researcher obtains a sample of n = 16 adults who are between the ages of 65 and 75. The researcher uses a standardized test to measure cognitive performance for each individual. The participants then begin a 2-month program in which they receive daily doses of a blueberry supplement. At the end of the 2-month period, the researcher again measures cognitive performance for each participant. The results show an average increase in performance of Mp = 7.4 with SS = 1215. a. Does this result support the conclusion that the antioxidant supplement has a significant effect on cognitive performance? Use a two-tailed test with a = = .05. (1) Ho: (Select] ( Select ] [ Select ] H: ( Select ] […arrow_forwardCadmium, a heavy metal, is toxic to animals. Mushrooms, however, are able to absorb and accumulate cadmium at high concentrations. The Czech and Slovak governments have set a safety limit for cadmium in dry vegetables at 0.5 part per million (ppm). M. Melgar et al. measured the cadmium levels in a random sample of the edible mushroom Boletus pinicola and published the results in the paper “Influence of Some Factors in Toxicity and Accumulation of Cd from Edible Wild Macrofungi in NW Spain” (Journal of Environmental Science and Health, Vol. B33(4), pp. 439–455). A hypothesis test is to be performed to decide whether the mean cadmium level in Boletus pinicola mushrooms is greater than the government’s recommended limit. Hypothesis tests are proposed. For each hypothesis test,a. determine the null hypothesis.b. determine the alternative hypothesis.c. classify the hypothesis test as two tailed, left tailed, or right tailed.arrow_forwardThe article “Arsenic and Mercury in Lake Whitefish and Burbot Near the Abandoned Giant Mine on Great Slave Lake” (P. Cott, B. Zajdlik, et al., Journal of Great Lakes Research, 2016:223–232) presents measurements of arsenic concentrations in fish found in Northern Canada. In a sample of 8 whitefish caught in Yellowknife Bay, the mean arsenic concentration in the liver was 0.32 mg/kg, with a standard deviation of 0.05 mg/kg. Can you conclude that the mean arsenic concentration in whitefish in Yellowknife Bay is greater than 0.3 mg/kg?arrow_forward
- According to a certain government agency for a large country, the proportion of fatal traffic accidents in the country in which the driver had a positive blood alcohol concentration (BAC) is 0.34. Suppose a random sample of 106 traffic fatalities in a certain region results in 48 that involved a positive BAC. Does the sample evidence suggest that the region has a higher proportion of traffic fatalities involving a positive BAC than the country at the a= 0.01 level of significance? .... Because npo (1- Po) =| 10, the sample size is 5% of the population size, and the sample the requirements for testing the hypothesis satisfied. (Round to one decimal place as needed.) What are the null and alternative hypotheses? versus H1: Ho: (Type integers or decimals. Do not round.) Find the test statistic, zo. Zo = (Round to two decimal places as needed.) Find the P-value. P-value = (Round to three decimal places as needed.) %3D Determine the conclusion for this hypothesis test. Choose the correct…arrow_forwardThe article "Vehicle-Arrival Characteristics at Urban Uncontrolled Intersections" (V. Rengaraju and V. Rao, Journal of Transportation Engineering, 1995: 317-323) presents data on traffic characteristics at 10 intersections in Madras, India. One characteristic measured was the speeds of the vehicles traveling through the intersections. The accompanying table gives the 15th, 50th, and 85th percentiles of speed (in km/h) for two intersections. Percentile Intersection 15th 50th 85th 27.5 37.5 40.0 в 24.5 26.5 36.0 If a histogram for speeds of vehicles through intersection A were drawn, would it most likely be skewed to the left, skewed to the right, or approximately symmetric? Explain. b. If a histogram for speeds of vehicles through intersection B were drawn, would it most likely be skewed to the left, skewed to the right, or approximately symmetric? Explain. a.arrow_forwardDoes buttered toast fall face down? Data was collected to test this. 40 slices of toast (each with butter on one side) were dropped (from the same height). 24 slices (60%) landed buttered side down. We would like to use the results of this study to determine if there is statistical evidence that toast tends to land buttered side down more than 50% of the time.arrow_forward
- According to a certain government agency for a large country, the proportion of fatal traffic accidents in the country in which the driver had a positive blood alcohol concentration (BAC) is 0.37. Suppose a random sample of 115 traffic fatalities in a certain region results in 56 that involved a positive BAC. Does the sample evidence suggest that the region has a higher proportion of traffic fatalities involving a positive BAC than the country at the a = 0.1 level of significance? Find the test statistic, zo. 20 = (Round to two decimal places as needed.)arrow_forwardAccording to a certain government agency for a large country, the proportion of fatal traffic accidents in the country in which the driver had a positive blood alcohol concentration (BAC) is 0.37. Suppose a random sample of 115 traffic fatalities in a certain region results in 56 that involved a positive BAC. Does the sample evidence suggest that the region has a higher proportion of traffic fatalities involving a positive BAC than the country at the a = 0.1 level of significance? Find the test statistic, zo. zo = 2.59 (Round to two decimal places as needed.) Find the P-value. P-value = (Round to three decimal places as needed.)arrow_forwardThe U.S. Energy Information Administration claimed that U.S. residential customers used an average of 10,368 kilowatt hours (kWh) of electricity this year. A local power company believes that residents in their area use more electricity on average than EIA's reported average. To test their claim, the company chooses a random sample of 128 of their customers and calculates that these customers used an average of 10,745kWh of electricity last year. Assuming that the population standard deviation is 2198kWh, is there sufficient evidence to support the power company's claim at the 0.05 level of significance? Step 2 of 3 : Compute the value of the test statistic. Round your answer to two decimal places.arrow_forward
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