As I get questions about the Stats Final, I will post them here, prepended by the date/time that I post them. FAQs are in reverse chronological order (most recent first).
- 4:30pm Regarding Question 5, Part 8 :
Do you think these data satisfy the assumptions for regression? Say why or why not.Robyn brings to my attention that Parts 6, 7 are optional but that to accurately answer Part 8 you need to determine if the residuals are normal (hint hint). If you don’t do Parts 6,7, then you may choose to either skip Part 8 or speculate based on looking at the data distribtuion or your intuition about the data….
Sunday June 2:
- 11pm: I promised to give you a more precise way to interpret a chi-square test. For the bird-foraging example from Week 7, we were able to reject our null hypothesis, and conclude:
. Birds neither prefer nor avoid foraging in shrubs during either season (Chi-square, df=2 = 15.04, Chi2critical=5.991, p < 0.05).on the final, you need not give the Chi2critical
- 11am: This question asked about Question 2, which is to “check the results of the t-test with resampling”. Question: There are multiple types of resampling, however, and I don’t know which one to use or how to use it in JMP. Can I have some clarification here?”
– response: you will use resampling in Excel (we did NO resampling in JMP). recall that a t-test essentially tests if two means are equal. the stats lab from week 3 ( look at Question 4) tells you how to do this with resampling in Excel.
- Question 1 has an error on Part 2. It should read:
2. State the null and alternative hypotheses for a statistical test of the claim that Malathion-treated plots have less beetle damage on oats.
- On Question 6,
Part 6 should read: Run the CHI-SQUARE (in JMP or Excel) and report your results.
Part 7 should be deleted.
Wed.5/29, 10:30pm – Question: The first paragraph appears to be about cereal leaf beetles and the use of Malathion. question #2 is asking for the null and alt hypotheses on the weight gain of chicks eating high-lysine corn. question #4 is about confidence interval of beetle larvae. I don’t see a data file for the cereal leaf beetle/Malathion, The high-lysine file does exist. Should JMP be run on this file?
Answer1: Be aware that the spreadsheet has several worksheets. I originally named the worksheets for the ordering of the questions in the first draft, but didn’t change the data when I uploaded the final draft of the exam, so the Qx on the worksheet does not agree with the Qx on the exam. However, I believe all the datasets are there, in the spreadsheet.
On Thursday morning I will upload a new .xlsx file and have renamed the worksheets so they are correctly numbered AND explicitly say which problem corresponds to which data sheet. Sorry.
Answer 2: Whether you run JMP or Resampling in Excel depends on your preference and whether the data meet the requirements for a parametric ANOVA…. If you can’t figure out for sure whether the data meets the requirements, then feel free to run a JMP if you wish. You’ll get credit for that part. Note that a resampling (monte carlo) test (rather than parametric) is always OK even if the data set is parametric. See why?