The ability to estimate the volume of a tree based on a simple measurement, such as the tree’s diameter, is important to the lumber industry, ecologists, and conservationists. Data on volume, in cubic feet, and diameter at breast height, in inches, for 70 shortleaf pines were reported in C. Bruce and F. X. Schumacher’s Forest Mensuration (New York: McGraw-Hill, 1935) and analyzed by A. C. Akinson in the article “Transforming Both Sides of a Tree” (The American Statistician, Vol. 48, pp. 307–312).
a) Obtain a scatterplot for the data.
b) Decide whether finding a regression line for the data is reasonable. If so, then also do parts (c)-(f).
c) Determine and interpret the regression equation for the data.
d) Identify potential outliers and influential observations.
e) In case a potential outlier is present, remove it and discuss the effect.
f) In case a potential influential observation is present, remove it and discuss the effect.