Homework 5

Course

STAT218

Due

February 4, 2025

  1. The table and figures below show summary statistics and distributions of clutch sizes for two of the sites in the frog data from Test 1.

    1. Compute a point estimate and standard error for the difference in mean clutch sizes between the two sites.
    2. Compute the test statistic you would use to test whether mean clutch size differs by site.
    3. Construct an approximate 99% confidence interval for the difference in mean clutch sizes.
    4. What would the conclusion of the test be at the 1% level?

site altitude csize.mean csize.sd n
063 3,098 625.67 197.01 23
077 2,035 733.44 202.72 37

Do this one by hand based on the output above. You can, if you wish, perform calculations in R in the cell below.

  1. [your answer here]
  2. [your answer here]
  3. [your answer here]
  4. [your answer here]
  1. The lizards data contains top running speeds in meters per second (m/s) from two species of lizard: western fence and sagebrush.

    1. Construct side-by-side boxplots and comment on whether there appears to be a difference in mean top running speed between species. If so, which species appears to run faster?
    2. Test for a difference in mean top running speed between species at the 5% level. Report the test result following conventional style.
    3. Compute a point estimate for the difference in means and a standard error. Report the estimate following conventional style.
    4. Construct and interpret an interval estimate consistent with your test.
# import data
load('data/lizards.RData')

# side-by-side boxplots

# test for a difference in mean top speed

# point estimate and standard error

# confidence interval
  1. [your answer here]
  2. [your answer here]
  3. [your answer here]
  4. [your answer here]