Class problems 4. The forest in the northern United States and Canada have no na
ID: 3316497 • Letter: C
Question
Class problems 4. The forest in the northern United States and Canada have no native terrestrial earthworms, but many exotic species have been introduced. These immigrant species are dramatically changing the soil. The following data were gathered to predit the N content of mineral soils of 39 hardwood forest plots in Michigan from the number of earthworm species foundfon this plot 5 Calculate the regression line to predict the total N content of the soil from the number of earthworm species a) 0.22, 0.19, 0.16, 0.08, 0.05 0.33, 0.30, 0.26, 0.24, 0.20, 0.18, 0.14, 0.13, 0.11, 0.09, 0.08 20.27,0.24,0.23,018,0.16,0.13 b) What are the units of your estimate of the slope? What is the predicted N content of soil having 5 earthworm species? 0.32, 0.32, 0.29, 0.24. 0.22, 0.12, 0.40 c) 0.34, 0.33, 0.23, 0.21. 0.18 D.17, 0.15. 0.14 X-# 2.205 Yn= 0.215 n=39 S(X-X- 86359 S(Y-Ym)2 = 0.366 s(X-X)(Y-Ym) = 2543 0.2, 0.54Explanation / Answer
a) The regression model can be built by running the following code in R:
n_species<-c(0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,5,5)
n_content<-c(0.22,0.19,0.16,0.08,0.05,0.33,0.3,0.26,0.24,0.2,0.18,0.14,0.13,0.11,0.09,0.08,
0.27,0.24,0.23,0.18,0.16,0.13,0.32,0.32,0.29,0.24,0.22,0.12,0.4,0.34,0.33,0.23
,0.21,0.18,0.17,0.15,0.14,0.2,0.54)
model<-lm(n_content~n_species)
The regression line is : N_content= 0.151977 + 0.028406* N_species
b) The units of the estimate of the slope are (N_content / N_species)
c) N_content = 0.151977 + 0.028406*5 = 0.294007