Biggest Shocker?

[durito]

I really wish I hadn't just re-read this thread.

I feel dumber.

[square1]

y	X1	X2

2	3	-3
3	6	-5
4	9	7
5	5	-2
6	5	5
7	8	-5
8	4	4
9	10	5
10	14	-7
11	18	6
13	15	-5

Regress X1 on y.

Now regress X1 and X2 on y.

Please do not tell your students that R-squared always increases when additional variables are added. I've found they are somewhat gullible regarding things like this, especially those in non-analytical fields.