# Minimum n for Chi square Test?

#### vier.gewinnt

##### New Member
Hey folks,

I'm currently evaluating the data of a study we performed.
Just got a very simple question: Is the a minimum number of subject neccessary to perform a Chi square test. I mean, I believe there should be, as you are splitting the group in 4 groups when performing the test...
But does anybody know wheather there is such a cut - off number?

Would be glad for any help you might offer,

Regards

vier.gewinnt

#### TheEcologist

##### Global Moderator
The minimum number of groups required to do a chi-squared is 2. 2 observed groups and 2 expected values.

Look at the formula for the degrees of freedom, it cant be less than 1.
http://en.wikipedia.org/wiki/Chi-square_test

Now there is a recommendation: namely the minimum expected value in any group should never be less than 5.

I hope I got your question because:

I mean, I believe there should be, as you are splitting the group in 4 groups when performing the test.
Is kind off vague.

#### vier.gewinnt

##### New Member
ok, thx!

In my case n is 12,the Table looks like this:

2 6

4 0

So I suspect, Chi Square is no good here..

vier.gewinnt...