Chapter 19 Week 4 - Reading questions

Reference

Miller, G. A., & Chapman, J. P. (2001). Misunderstanding analysis of covariance. Journal of Abnormal Psychology, 110(1), 40-48.

Questions:

1. What was the original purpose of ANCOVA?
2. In the intro two problems are mentioned which may arise when ANCOVA is used in the context of existing groups. Which problems are these, and why are these problems?
3. On p. 44 a hypothetical statistician is discussed (introduced by Lord) who uses ANCOVA to compare the weight of boys and girls, while using initial weight as a covariate. How does this statistician use ANCOVA exactly, and why is this wrong?
4. Why is comparing young women to old men problematic (p. 44)?
5. In the example discussed on p. 46 (first column), what is the DV, the covariate(s) and the grouping variable? Is this a good example of the problem the authors try to point out, and why do you think it is/is not?