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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- The 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. Use the technology of your choice to a. obtain frequency and relative-frequency distributions, using single-value grouping. b. construct and interpret either a frequency histogram or a relativefrequency histogram.arrow_forwardResearchers measured the distribution of beak sizes in a cohort of medium ground finch hatchlings in the Galapagos Islands in 1976 just before, and in a cohort of hatchlings two years after a severe drought. They measured 100 finches in each cohort. After the drought, the proportion of large, harder seeds was substantially greater than before the drought. Their data documenting this selective event are shown in graphical and tabular form below. Beak size (mm) Frequency before selection Frequency after selection 10.010.0 0.000.00 0.000.00 10.210.2 0.000.00 0.000.00 10.410.4 0.020.02 0.000.00 10.610.6 0.040.04 0.000.00 10.810.8 0.080.08 0.000.00 11.011.0 0.160.16 0.000.00 11.211.2 0.200.20 0.000.00 11.411.4 0.200.20 0.000.00 11.611.6 0.160.16 0.020.02 11.811.8 0.080.08 0.040.04 12.012.0 0.040.04 0.080.08 12.212.2 0.020.02 0.160.16 12.412.4 0.000.00 0.200.20 12.612.6 0.000.00 0.200.20 12.812.8 0.000.00 0.160.16 13.013.0 0.000.00 0.080.08 13.213.2…arrow_forwardThe article "Time Series Analysis for Construction Productivity Experiments" (T. Abdelhamid and J. Everett, Journal of Construction Engineering and" Management, 1999:87–95) presents a study comparing the effectiveness of a video system that allows a crane operator to see the lifting point while operating the crane with the old system in which the operator relies on hand signals from a tagman. Three different lifts, A, B, and C, were studied. Lift A was of little difficulty, lift B was of moderate difficulty, and lift C was of high difficulty. Each lift was performed several times, both with the new video system and with the old tagman system. The time (in seconds) required to perform each lift was recorded. The following tables present the means, standard deviations, and sample sizes. Low Difficulty Mean Standard Deviation Sample Size Tagman 47.79 2.19 14 Video 47.15 2.65 40 Moderate Difficulty Mean Standard Deviation Sample Size Tagman 69.33 6.26 12 Video 58.50 5.59 24 High Difficulty…arrow_forward
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- A 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 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_forwardQ. No. 3: Recently airlines have cut services, such as meals and snacks during flights, and started charging extra for some services, such as accommodating overweight luggage, last-minute flight changes, and pets traveling in the cabin. However, they are still concerned about service. Recently, a group of four carriers hired Brunner Marketing Research Inc. to survey passengers regarding their level of satisfaction with a recent flight. The survey included questions on ticketing, boarding, in-flight service, baggage handling, pilot communication, and so forth. Twenty-five questions offered a range of possible answers: excellent, good, fair, or poor. A response of excellent was given a score of 4, good a 3, fair a 2, and poor a 1. These responses were then totaled, so the total score was an indication of the satisfaction with the flight. The greater the score, the higher the level of satisfaction with the service. The highest possible score was 100. Brunner randomly selected and surveyed…arrow_forward
- us. 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_forwardIn a study of hypnotic suggestion, 16 male volunteers were randomly allocated to a treatment groupand a control group. Each subject participated in a two-phase experimental session. In the first phase, respiration was measured while the subject was awake and at rest. In the second phase, the subject was told to imagine that he was performing muscular work, and respiration was measured again. For subjects in the treatment group, hypnosis was induced between the first and second phases; thus, the suggestion to imagine muscular work was “hypnotic suggestion” for treatment subjects and “waking suggestion” for control subjects. The table below shows the measurements of total ventilation (liters of air per minute per square meter of body area) for all 16 subjects. (a) For those being hypnotized (treatment group), test the hypotheses H0: μrest = μwork versus Ha:μrest 6= μwork, where μrest and μwork are respectively the mean total ventilation when they are atrest and when they are performing…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
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