Refer to the Evolutionary Ecology Research (July 2003) study of the New Zealand bird population prior to European contact, Exercise 1.12. Two quantitative variables measured for each of The 116 bird species were body mass (grams) and egg length (millimeters). Descriptive statistics for these variables are shown on the MINITAB printout above. 

a. Use a random number generator to select a random sample of 35 species from the NZBIRDS file.

b. Calculate the mean and standard deviation for the 35 sampled values of body mass. Then, use this information to construct a 95% confidence interval for the mean body mass of all 116 bird species. 

c. Give a practical interpretation of the interval, part b.

d. Check to see if the true mean, m (shown on the MINITAB printout), is included in the confidence interval, part b. Explain why the interval is very likely to contain m. 

e. Repeat parts b–d for the 35 sampled values of egg length.

f. Ecologists also want to compare the proportions of flightless birds for two New Zealand bird populations— those that are extinct and those that are not extinct. Use the sample information in the table below to form a 95% confidence interval for the difference between the proportion of flightless birds for extinct and nonextinct species.

g. The ecologists are investigating the theory that the proportion of flightless birds will be greater for extinct species than for nonextinct species. Does the confidence interval, part f, support this theory? Explain.

Data from Exercise 1.12

Environmental engineers at the University of California (Riverside) are studying the patterns of extinction in the New Zealand bird population. (Evolutionary Ecology Research, July 2003.) The following characteristics were determined for each bird species that inhabited New Zealand at the time of the Maori colonization (i.e., prior to European Contact). Identify each variable as quantitative or qualitative.

Transcribed Image Text:

Descriptive Statistics: Body Mass, Egg Length Variable N Mean StDev Minimum Maximum Body Mass 116 9113 31457 7.00 200000 Egg Length 115 61.06 45.46 16.00 236.00