In a study of diet preferences in leafcutter ants, a researcher presented 20 randomly chosen ant colonies with leaves from the two most common tree species in the surrounding forest. The leaves were placed in piles of 100, one pile for each tree species, close to colony entrances. Leaves were cut so that each was small enough to be carried by a single ant. After 24 hours, the researcher returned and counted the number of leaves remaining of the original 100 of each species. Some of the results are shown in the following table.

Using these results, the researcher estimated the proportion of Spondius mombin leaves taken as 0.65 and concluded that the ants have a preference for leaves of this species.

a. Identify the two variables whose association is displayed in the table.

Which is the explanatory variable and which is the response variable?

Are they numeric or categorical?

b. Why do the 2412 leaves used in the calculation of the proportion not represent a random sample?

c. Would treating the 2412 leaves as a random sample most likely affect the accuracy of the estimate of diet preference or the precision of the estimate?

d. If not the leaves, what units were randomly sampled in the study?

Transcribed Image Text:

Tree species Spondius mombin Spondius mombin Sapium thelocarpum Sapium thelocarpum TotalTotal Number of leaves removed 15611561 851851 24122412