Northern flying squirrels eat lichen and fungi, which makes for a relatively low quality diet. The authors of the paper €œNutritional Value and Diet Preference of Arboreal Lichens and Hypogeous Fungi for Small Mammals in the Rocky Mountains€(Canadian Journal of Zoology [ 2008]: 851€“ 862) measured nitrogen intake and nitrogen retention in six flying squirrels that were fed the fungus Rhizopogon. Data from a graph in the paper are given in the following table. (The negative value for nitrogen retention for the first squirrel represents a net loss in nitrogen.)

a. Construct a scatterplot of these data.
b. Find the equation of the least squares regression line. Based on this line, what would you predict nitrogen retention to be for a flying squirrel whose nitrogen intake is 0.06 grams? What is the residual associated with the observation (0.06, 0.01)?
c. Look again at the scatterplot from Part (a). Which observation is potentially influential? Explain the reason for your choice.
d. When the potentially influential observation is deleted from the data set, the equation of the least squares regression line fit to the remaining five observations is ˆy= 20.037 1 0.627x. Use this equation to predict nitrogen retention for a flying squirrel whose nitrogen intake is 0.06. Compare this prediction to the prediction made in Part (b).

Transcribed Image Text:

Nitrogen Intake Nitrogen Retentlorn x (grams) 0.03 0.10 0.07 0.06 0.07 0.25 y (grams) -0.04 0.00 0.01 0.01 0.04 0.11