Thought the lost-socks-due-to-alien-burglary anecdote was cute (see previous post), I need a little more instruction. Dr. S explained that a null hypothesis is: "there is no difference between X and Y." I found this on ehow.com - How to Write a Null Hypothesis.

Summarized:
- Write the hypothesis (i.e., what I believe to be true). Let's say my belief is the old adage: You can't teach an old dog new tricks.
- Turn this into a statement that indicates no difference between experimental groups: Old dogs and younger dogs can (or can't) learn new tricks.