Inch Lake is a 12.5 ha inland lake in northern Wisconsin that has been managed as catch-and-release for all species since 2006. Researchers at Northland College have monitored fish populations in Inch Lake since 2007. The total lengths (inches) and weights (g) for subsamples of several species of fish collected from Inch Lake in May of 2007 and 2008 are recorded in InchLake2.csv (view, download, meta).

Load these data, isolate Bluegill, and answer the following questions.

  1. Complete this Plotting exercise.
    1. Describe the relationship between weight and length (in mm here and throughout).
    2. Describe the relationship between log-transformed weight and length.
  2. Compute the weight-length relationship with an appropriate linear regression.
    1. Plot the results (data and the fitted relationship) on both the transformed and raw scales. Comment on the fit.
    2. Construct a residual plot. Comment.
    3. Express your results as an equation on the transformed scale.
    4. Express your results as an equation on the raw scale.
    5. Carefully interpret the meaning of the slope of the weight-length relationship.
    6. Is there statistical evidence for isometric or allometric growth?
  3. Recompute the weight-length relationship using the original length in inches. How do the slope and y-intercept from this model compare to the results from the previous question?

Continue with these data for weight-length comparisons and condition exercises.

from Derek H. Ogle , created 08-Mar-19, updated 26-Dec-21, Comments/Suggestions.