Refer to the Landscape & Ecology Engineering (Jan. 2013) study of hippopotamus grazing patterns in Kenya, Exercise 7.41. Recall that plots of land were sampled in two areas — a national reserve and a pastoral ranch — and the number of hippo trails from a water source was determined for each plot. Sample statistics are reproduced in the next table.
a. Find an interval estimate of σ₁²/σ₂², the ratio of the variances associated with the two areas. Use a 90% confidence level.

b. Can the researchers reliably conclude that the variability in number of hippo trails from a water source in the national reserve differs from the variability in number of hippo trails from a water source in the pastoral ranch? Explain.

Data from Exercise 7.41

In Kenya, human-induced land-use changes and excessive resource extraction has threatened the jungle ecosystem by reducing animal grazing areas and disrupting access to water sources. In Landscape & Ecology Engineering (Jan. 2013), researchers compared hippopotamus grazing patterns in two Kenyan areas — a national reserve and a community pastoral ranch. Each area was subdivided into plots of land. The plots were sampled (406 plots in the national reserve and 230 plots in the pastoral ranch) and the number of hippo trails from a water source was determined for each plot. Sample statistics are provided in the table. The researchers concluded that the mean number of hippo trails was higher in the national reserve than in the pastoral ranch.

Transcribed Image Text:

National Reserve Pastoral Ranch Sample size: 406 230 Mean number of trails: 0.31 0.13 Standard deviation: 0.4 0.3