Mercury Concentration in DolphinsBecause dolphins (and other large marinemammals) are

Chapter 13, Problem 29

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Mercury Concentration in DolphinsBecause dolphins (and other large marinemammals) are considered to be the top predators inthe marine food chain, the heavy metal concentrationsin striped dolphins were measured as part of amarine pollution study. The concentration of mercury,the heavy metal reported in this study, isexpected to differ in males and females because themercury in a female is apparently transferred to heroffspring during gestation and nursing. This studyinvolved 28 males between the ages of .21 and 39.5years, and 17 females between the ages of .80 and34.5 years. For the data in the table, x1 Age of the dolphin (in years)0 if femalex2 1 if maley Mercury concentration (inmicrograms/gram) in the livery x1 x2 y x1 x21.70 .21 1 481.00 22.50 11.72 .33 1 485.00 24.50 18.80 2.00 1 221.00 24.50 15.90 2.20 1 406.00 25.50 1101.00 8.50 1 252.00 26.50 185.40 11.50 1 329.00 26.50 1118.00 11.50 1 316.00 26.50 1183.00 13.50 1 445.00 26.50 1168.00 16.50 1 278.00 27.50 1218.00 16.50 1 286.00 28.50 1180.00 17.50 1 315.00 29.50 1264.00 20.50 1y x1 x2 y x1 x2241.00 31.50 1 142.00 17.50 0397.00 31.50 1 180.00 17.50 0209.00 36.50 1 174.00 18.50 0314.00 37.50 1 247.00 19.50 0318.00 39.50 1 223.00 21.50 02.50 .80 0 167.00 21.50 09.35 1.58 0 157.00 25.50 04.01 1.75 0 177.00 25.50 029.80 5.50 0 475.00 32.50 045.30 7.50 0 342.00 34.50 0101.00 8.05 0135.00 11.50 0a. Write a second-order model relating y to x1 and x2.Allow for curvature in the relationship between ageand mercury concentration, and allow for an interactionbetween gender and age.Use a computer software package to perform the multipleregression analysis. Refer to the printout toanswer these questions.b. Comment on the fit of the model, using relevantstatistics from the printout.c. What is the prediction equation for predicting themercury concentration in a female dolphin as afunction of her age?d. What is the prediction equation for predicting themercury concentration in a male dolphin as a functionof his age?e. Does the quadratic term in the prediction equationfor females contribute significantly to the predictionof the mercury concentration in a femaledolphin? f. Are there any other important conclusions that youfeel were not considered regarding the fitted predictionequation?