Friday
May 6, 2016

Homework Help: Statistics/Chi Square

Posted by Jaime on Wednesday, February 29, 2012 at 8:23pm.

I have a question to do in which the efficacy of a drug used to treat panic disorder is tested. Patients are given a placebo for one week and then the drug for one week, and the number of panic attacks is measured for each week. The data looks like this:

Placebo Drug
0 0
2 1
0 3
1 2
0 0
10 5
2 0
6 4
1 1
1 0
1 3
0 2
3 1
3 1
3 4
4 2
6 4
15 21
28 8
30 0
13 0
15 12
18 18
9 6
8 7
22 14
13 3
12 8
6 7
4 5
0 2

Where each line is a subject. I am pretty sure that I need to do a goodness-of-fit chi square test, where my null hypothesis is that the distribution of panic attacks on the drug is the same as (or greater than) the distribution of panic attacks on the placebo. My alternative hypothesis is that the distribution of panic attacks on the drug is less than the distribution of panic attacks on the placebo. I also know that the chi-square test statistic is found by ((O-E)^2)/E.

I'm confused about how to set up my categories to perform the chi-square test. I don't think I'm supposed to use the raw panic attack data shown above because that gives me some divide by zero errors when I try to calculate my test statistic. I tried to create a 2x2 grid (placebo vs. drug by no panic attack vs. panic attack) but that loses information about the number of panic attacks. Any advice?