Pitcher plants of the genus Nepenthes are typically carnivor

Pitcher plants of the genus Nepenthes are typically carnivorous, obtaining a great deal of their nutrition from insects that become trapped in the pitcher, die, and decay. N. lowii, a pitcher plant from Borneo, produces a second type of pitcher that attracts tree shrews (Tupaia montana), which provide nutrients by defacating into the pitcher while they feed on a substance secreted by the plant. Based on measurements of 20 plants, Clarke et al. (2009) calculated 95% confidence interval for the mean fraction of total leaf nitrogen in the plant species derived from tree shrews: 0.57 < u < 1.0.

a. Does this result imply that individual plants receive 57% and 100% of their leaf nitrogen from tree shrews? Explain.

b. Is the confidence interval meant to bracket the sample mean or the population mean?

c. Identify two values for the mean shrew fraction of total leaf nitrogen that the analysis suggests are among the most plausible.

d. Identify two values for the mean shrew fraction of total leaf nitrogen that the analysis suggests are less plausible.

Solution

A. No, this does not imply that individual plants receive between 57% and 100% of their nitrogen from tree shrews. It means that we are 95% confident that the true population mean is between .57 and 1

B. The confidence interval brackets the population mean.

C. Among the most plausible would be anything from .7 to .8 since they are in the center of the confidence interval.

D. Values least plausible would be anything less than .57 or greater than 1.0