Okay, so I have a Univariate Statistics test tomorrow morning. I'm going through the practice problems that the professor posted online, and I'm a little confused about one of the problems.
The problem is:
6. Orthogonal Comparisons
Compare Group D to the other three groups.
Group A raw data: 5 5 4 3 (total=17)
Group B raw data: 4 2 4 4 (total=14)
Group C raw data: 9 9 8 7 (total=33)
Group D raw data: 9 7 7 7 (total=30)
The SSbetween for this problem = 66.25 and the SSwithin = 11.50
When I calculate this out, I get the sums of squares to be 28.166... But on the answer key to the practice problems, the sums of squares is listed as 14.0833..., which is exactly half of what I got. This happens even when I punch the exact steps that the answer key lists into my calculator, which leads me to believe that there's some sort of step that's supposed to be obvious or implicit that I'm overlooking. What I need to know is, after I do:
Do I just divide the answer by 2 every time, or is there something I need to do to figure out how much I need to divide by? All of the practice problems use the same set of data or I could figure this out on my own.
What makes it even more confusing is that a later problem asks to compare Group A to Group B, and on that one I calculate the same sums of squares as the answer key without needing to do any dividing.
Help would be appreciated! Hopefully what I typed was coherent enough for someone to understand!