K300, Prof. Kruschke K300 Statistics, Prof. Kruschke

Homework 9, Due at the beginning of class, Tuesday April 19, 2005.

Be sure to

  • write your name and ID on every page
  • make a copy of your homework for your own records and exam study
  • staple (not paper clip) your pages
  • write clearly
  • show your work as appropriate -- an unannotated sequence of numbers and derivations that mysteriously ends up with the correct numerical answer will not be given full credit
  • answer every part of every question (unless instructed otherwise).

    1. 5 pts. Page 329, #14. Do not use the .01 level; use the .05 level. And answer this: Why does SSB change from part (a) to part (b), but SSW does not?

    2. 5 pts. Page 329, #17. For part (a), just show you work clearly; do not bother with the exact steps of hypothesis testing. Do part (b). Do not do part (c).

    3. 5 pts. What is the definition of effect size for single-factor ANOVA? Express your answer in words and as a formula that does not explicitly involve n (the sample size per group).

    4. 5 pts. Page 329, #18.

    5. 5 pts. What are three ways to increase the power of a single-factor ANOVA? (Hint: These are exactly analogous to the three ways to increase power for a t test.)

    6. 5 pts. Page 329, #19.

    7. 5 pts. For the following three groups of scores, conduct a one-way ANOVA (a) by hand and (b) in Excel. (c) Estimate the effect size.
         Group 1: 2, 4, 7, 9
         Group 2: 1, 3, 5
         Group 3: 6, 8, 10
      Notice that the sample sizes are not the same in the three groups, so you will need to use the formulas for F described in class. Show your work. For your Excel print out, print just one page that includes the data and the ANOVA results.

    8. 5 pts. Suppose we are interested in salaries of associate professors (i.e., typically 7-12 years as faculty, post PhD) in various departments. Below are some data; conduct a oneway ANOVA in Excel, print out a page showing the data and the ANOVA, and write your conclusion.
      Applied Health Science: 81780 76127 75037 74100 72677 71535 71200 71028 70268 69608 65601
      Counseling and Educational Psychology: 108388 80387 78052 77928 74765 72188 71827 68709 65155 59354
      Criminal Justice: 73327 71820 64624 64185 63782 62519 59589 59041 58534 56445
      Journalism: 72875 68180 66870 65620 65470 65135 64840 64230
      Psychology: 61534 61488 58287 56989 56599 61308