Data analysis and write-up
Population Ecology: Salamanders and earthworms
Before completing this assignment you need to fully understand t-tests and chi-squared tests.
For this assignment, you should use the appropriate statistical test to evaluate the stated
hypotheses. Show all work and use the tables in the back of your text to assess significance. Alternatively, you may use excel functions to perform the relevant tests. Use alpha cutoff values of 0.05 for the interpretation of p-values. Use two-tailed tests for these analyses.
Using the class data sheet (posted on course site), you should assess each hypothesis listed below. For each question A)
State whether or not you can reject or tentatively support each hypothesis, B)
report the relevant statistics (the test you used and the p-value), C)
show any calculations or screenshot your excel sheet including any formulas, and D)
in a couple sentences state why you think the difference (or lack of difference) was observed. The data are
arranged in different sheets of the excel file. 1)
The average size of earthworms is significantly greater under deciduous canopies in the interior of the forest than under pine-dominated canopies near the edge of the forest (hypothesis).
2)
The abundance of earthworms is significantly greater under deciduous canopies in the interior of the forest than under pine canopies near the edge (hypothesis).
3)
The abundance of earthworms was greater in 2019-2021 than it was in 2022-2023.
4)
Salamanders are significantly more abundant under deciduous canopies in the interior of the forest than under pine-dominated canopies near the edge (hypothesis). 5)
The average size of salamanders is significantly different under areas of the forest dominated by pines and hardwoods (hypothesis).
Extra credit +1:
Do some research on one-tailed versus two-tailed t-tests. Why would a researcher use a 1-tailed versus a 2-tailed test?
