Since a number of students are out due to the football game/etc, here is the powerpoint from class which walks through the bulk of chapter 13 in the textbook.

• 13 Student Notes - Experiments and Observational Studies.ppt

Of course, you could also read through chapter 13 in the textbook~

HW #7 is due next time.  Ignore the worksheet on the calendar for today (Fish tank), we'll do that on a later date.