In the Department of Fisheries and Wildlife at Virginia

Chapter 12, Problem 12.62

(choose chapter or problem)

In the Department of Fisheries and Wildlife at Virginia Tech, an experiment was conducted to study the eect of stream characteristics on sh biomass. The regressor variables are as follows: average depth (of 50 cells), x1; area of in-stream cover (i.e., undercut banks, logs, boulders, etc.), x2; percent canopy cover (average of 12), x3; and area 25 centimeters in depth, x4. The response is y, the sh biomass. The data are as follows: Obs. yx 1 x2 x3 x4 1 2 3 4 5 6 7 8 9 10 100 388 755 1288 230 0 551 345 0 348 14.3 19.1 54.6 28.8 16.1 10.0 28.5 13.8 10.7 25.9 15.0 29.4 58.0 42.6 15.9 56.4 95.1 60.6 35.2 52.0 12.2 26.0 24.2 26.1 31.6 23.3 13.0 7.5 40.3 40.3 48.0 152.2 469.7 485.9 87.6 6.9 192.9 105.8 0.0 116.6 (a) Fit a multiple linear regression including all four regression variables. (b) Use Cp, R2, and s2 to determine the best subset of variables. Compute these statistics for all possible subsets. (c) Compare the appropriateness of the models in parts (a) and (b) for predicting sh biomass.