A biologist measured the post-orbital carapace length (mm) for specimens of two species of crayfish: Rusty crawfish and Sanborn crawfish. Summary statistics are given below.44

For these data, SS(Sex) = 11.5 SS(Species) = 198.8. SS(interaction) = 113.5, and SS(within) = 482.7.
(a) Prepare an interaction graph (like Figure 11.7.3) to investigate whether the male versus female difference is the same for Rusty as for Sanborn crayfish.
(b) Does the interaction graph from part (a) suggest that there is an interaction present? If so, what does that mean? If not, what does that mean?
(c) Carry out an F test for interactions; use α = 0.10.
(d) Given the result of the test in part (c), is it appropriate to test the null hypothesis that species has no effect on carapace length? If so, then conduct that test using α = 0.05. If not, then explain why not.

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Rusty Rusty, Sanborn, Sanborn, female malefemale male Mean 16.78 21.62 16.6415.69 2.81 4.261762.45 SD 13 14 28