Concept explainers
Delaying Adulthood. In the paper, “Delayed Metamorphosis of a Tropical Reef Fish (Acanthurus triostegus): A Field Experiment” (Marine Ecology Progress Series, Vol. 176, pp. 25–38), M. McCormick studied larval duration of the convict surgeonfish, a common tropical reef fish. This fish has been found to delay metamorphosis into adulthood by extending its larval phase, a delay that often leads to enhanced survivorship in the species by increasing the chances of finding suitable habitat. Duration of the larval phase for convict surgeonfish is
- a. Sketch the normal curve for the variable x.
- b. Simulate 1500 observations of x. (Note: Users of the TI-83/84 Plus should simulate 750 observations.)
- c. Approximately what values would you expect for the sample mean and sample standard deviation of the 1500 observations? Explain your answers.
- d. Obtain the sample mean and sample standard deviation of the 1500 observations, and compare your answers to your estimates in part (c).
- e. Roughly what would you expect a histogram of the 1500 observations to look like? Explain your answer.
- f. Obtain a histogram of the 1500 observations, and compare your result to your expectation in part (e).
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- Beryllium disease: Beryllium is an extremely lightweight metal that is used in many industries, such as aerospace and electronics. Long-term exposure to beryllium can cause people to become sensitized. Once an individual is sensitized, continued exposure can result in chronic beryllium disease, which involves scarring of the lungs. In a study of the effects of exposure to beryllium, workers were categorized by their duration of exposure (in years) and by their disease status (diseased, sensitized, or normal). The results were as follows: Duration of Exposure 5 Diseased 15 7. 19 Sensitized 12 22 14 Normal 66 145 197 Send data to Excel Test the hypothesis of independence. Use the a = 0.10 level of significance and the P-value method with the TI-84 Plus calculator. What do you conclude?arrow_forwardA local church is interested in determining how length of residence in the present community relates to church attendance. Using a random sample of 15 individuals, they gathered data on how many times in the previous 5 weeks each individual attended church services. The data are provided below. Length of residence in the community Less than 2 years 2-5 years More than 5 years 0 0 1 1 2 3 3 3 3 4 4 4 4 5 4 Using the 5-step model, determine whether and how church attendance is related to length of residence in the community. Use 5% and 1% levels of statistical significance. What are the assumptions for this problem?arrow_forwardIn an article in the Journal of Marketing, Bayus studied the differences between "early replacement buyers" and "late replacement buyers" in making consumer durable good replacement purchases. Early replacement buyers are consumers who replace a product during the early part of its lifetime, while late replacement buyers make replacement purchases late in the product's lifetime. In particular, Bayus studied automobile replacement purchases. Consumers who traded in cars with ages of zero to three years and mileages of no more than 35,000 miles were classified as early replacement buyers. Consumers who traded in cars with ages of seven or more years and mileages of more than 73,000 miles were classified as late replacement buyers. Bayus compared the two groups of buyers with respect to demographic variables such as income, education, age, and so forth. He also compared the two groups with respect to the amount of search activity in the replacement purchase process. Variables compared…arrow_forward
- In an article in the Journal of Marketing, Bayus studied the differences between "early replacement buyers" and "late replacement buyers" in making consumer durable good replacement purchases. Early replacement buyers are consumers who replace a product during the early part of its lifetime, while late replacement buyers make replacement purchases late in the product's lifetime. In particular, Bayus studied automobile replacement purchases. Consumers who traded in cars with ages of zero to three years and mileages of no more than 35,000 miles were classified as early replacement buyers. Consumers who traded in cars with ages of seven or more years and mileages of more than 73,000 miles were classified as late replacement buyers. Bayus compared the two groups of buyers with respect to demographic variables such as income, education, age, and so forth. He also compared the two groups with respect to the amount of search activity in the replacement purchase process. Variables compared…arrow_forwardA survey was conducted to evaluate the effectiveness of a new flu vaccine that had been administered in a small community. The vaccine was provided free of charge in a two-shot sequence over a period of 2 weeks. Some people received the two-shot sequence, some appeared for only the first shot, and others received neither. A survey of 1000 local residents the following spring provided the information shown in Table 14.6. Do the data present sufficient evidence to indicate that the vaccine was successful in reducing the number of flu cases in the community? 2 x 3 Contingency Table Flu No Flu Total No Vaccine One Shot Two Shots 24 289 313 9 100 109 13 565 578 Total 46 954 1000arrow_forwardIn his doctoral thesis, L. A. Beckel (University of Minnesota, 1982) studied the social behavior of river otters during the mating season. An important role in the bonding process of river otters is very short periods of social grooming. After extensive observations, Dr. Beckel found that one group of river otters under study had a frequency of initiating grooming of approximately 1.7 for each 10 minutes. Suppose that you are observing river otters for 30 minutes. Let r = 0, 1, 2, ... be a random variable that represents the number of times (in a 30-minute interval) one otter initiates social grooming of another. a) Find the probabilities that in your 30 minutes of observation, one otter will initiate social grooming four times, five times, and six times. (Round your answers to four decimal places.) P(4) = P(5) = P(6) = b) Find the probability that one otter will initiate social grooming less than four times during the 30-minute observation period. (Round your answer…arrow_forward
- An article in Urban Ecosystems, "Urbanization and Warming of Phoenix (Arizona, USA): Impacts, Feedbacks and Mitigation" (2002, Vol. 6, pp. 183-203), mentions that Phoenix is ideal to study the effects of an urban heat island because it has grown from a population of 300,000 to approximately 3 million over the last 50 years and this is a period with a continuous, detailed climate record. The 50-year averages of the mean annual temperatures at eight sites in Phoenix are shown below. Check the assumption of normality in the population with a probability plot. Construct a 90% confidence interval for the standard deviation over the sites of the mean annual temperatures. Site Sky Harbor Airport 23.3 Phoenix Greenway 21.7 Phoenix Encanto 21.6 Waddell Litchfield Laveen Average Mean Temperature (°C) Maricopa Harlquahala i 21.7 21.3 20.7 20.9 20.1 Round the answers to three decimal places. sosiarrow_forwardPart c of 6.2 only.arrow_forwardParents are frequently concerned when their child seems slow to begin walking (although when the child finally walks, the resulting havoc sometimes has the parents wishing they could turn back the clock!). An article on this topic reported on an experiment in which the effects of several different treatments on the age at which a child first walks were compared. Children in the first group were given special walking exercises for 12 minutes per day beginning at age 1 week and lasting 7 weeks. The second group of children received daily exercises but not the walking exercises administered to the first group. The third and fourth groups were control groups. They received no special treatment and differed only in that the third group's progress was checked weekly, whereas the fourth group's progress was checked just once at the end of the study. Observations on age (in months) when the children first walked are shown in the accompanying table. Age n Total Treatment 1 9.00 9.50…arrow_forward
- Appalachian Bear Rescue (ABR) is a not-for-profit organization located near the Great Smoky Mountains National Park. ABR's programs include the rehabilitation of orphaned and injured black bears, as well as research and education about Appalachian black bears. ABR provides the most natural environment possible for rehabilitating black bears before their release back into the wild. Recently, Katie Settlage performed a study to learn more about the Appalachian black bear population in the Great Smoky Mountains National Park. She and a team of researchers found 68 black bears in the park and took measurements such as paw size, weight, and shoulder height. The stem-and-leaf plots below show the shoulder heights (in centimeters) of the 40 male and 28 female bears from the study. Shoulder Heights (in cm) of Male Bears Shoulder Heights (in cm) of Female Bears 4 9 Key: 4 9 = 49 Key: 5|0 = 50 5 7 8 9 71 1 2 2 2 2 2 3 3 3 4 4 5 5 6 6 788 8 123 4 4 5 6 79 90 0 3 6 79 7 8 1 2 3 3 3 33 4 6 7 555 5…arrow_forwardus. What does this suggest? Source: Pegna, Alan J. et al., "Discriminating Emotional Faces without Primary Visual Cortices Involves the Right Amygdala." Nature Neuroscience, 8(1), 2005. 28. Reproducibility Researchers looked at studies that were reported in newspapers with the goal of determining whether initial studies had results that could be reproduced. Reproducibility of results means that subsequent analysis confirms the conclusion of the original study. Primary studies are studies where the researchers come up with a research objective, clearly state the goals of the study and population, describe the research method, test the research hypotheses, and draw conclusions. (a) Among the 156 primary studies reported by newspapers, 76 had results that were validated by subsequent analysis. Does this suggest less than a majority of initial studies reported by newspapers have their results validated by subsequent analysis? (b) In the article, a null effect is defined as any study where…arrow_forwardThe Great White Shark. In an article titled “Great White, Deep Trouble” (National Geographic, Vol. 197(4), pp. 2–29), Peter Benchley—the author of JAWS—discussed various aspects of the Great White Shark (Carcharodon carcharias). Data on the number of pups borne in a lifetime by each of 80 Great White Shark females are provided on the WeissStats site. a. obtain and interpret the quartiles. b. determine and interpret the interquartile range. c. find and interpret the five-number summary. d. identify potential outliers, if any. e. obtain and interpret a boxplot.arrow_forward
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- Elementary Statistics: Picturing the World (7th E...StatisticsISBN:9780134683416Author:Ron Larson, Betsy FarberPublisher:PEARSONThe Basic Practice of StatisticsStatisticsISBN:9781319042578Author:David S. Moore, William I. Notz, Michael A. FlignerPublisher:W. H. FreemanIntroduction to the Practice of StatisticsStatisticsISBN:9781319013387Author:David S. Moore, George P. McCabe, Bruce A. CraigPublisher:W. H. Freeman