Question

Damage to grapes from bird predation is a serious problem for grape growers. An article reported on an experiment involving a bird-feeder table, time-lapse video, and artificial foods. Information was collected for two different bird species at both the experimental location and at a natural vineyard setting. Consider the following data on time (sec) spent on a single visit to the location. (Note: Assume the populations are normally distributed.)

Species		Location		n		x		SE mean
Blackbirds		Exptl		30		13.9		2.04
Blackbirds		Natural		15		9.6		1.79
Silvereyes		Exptl		32		49.3		4.77
Silvereyes		Natural		29		38.5		5.08

c. Estimate the difference between the true average time blackbirds spend at the natural location and true average time that silvereyes spend at the natural location, and do so in a way that conveys information about reliability and precision. (Use a 95% confidence interval for μ_silvereyes − μ_blackbirds. Use α = 0.05. Round your answers to two decimal places.)

Answer 1