A number of studies have shown lichens (certain plants composed of an alga and a fungus) to be excellent bioindicators of air pollution. The article “The Biomonitor of Atmospheric Nitrogen and Sulphur Deposition in Norway” (Environ. Monit. Assess. 1993: 27–47) gives the following data (read from a graph) on x =  NO₃^– wet deposition (gN/m²) and y = lichen N (% dry weight):

The author used simple linear regression to analyze the data. Use the accompanying Minitab output to answer the following questions:
a. What are the least squares estimates of β₀ and β₁?
b. Predict lichen N for an NO₃ ^–deposition value of .5.
c. What is the estimate of σ?
d. What is the value of total variation, and how much of it can be explained by the model relationship?

Transcribed Image Text:

X y X y .05 .10 .48 .55 .58 .86 .68 .86 .11 .48 .68 1.00 .12 .31 .50 .58 .73 .88 .85 1.04 .37 .52 .92 1.70 .42 1.02