Chi square test

I'm writing an article on pyelonephritis in children and for this I've come across a statistical problem, seeing as my statistical skills are very limited.

My data is devided into three groups: group A: children younger than 6 months, Group B: Children between 6 months and 3 years, group C: children older than 3 years.
For these three groups I've found frequences of abnormal lab findings, abnormal ultrasound etc.
In order to compare these three groups statistically - as in: is the frequencies of abnormal lab findings or abnormal ultrasound significantly different? - I've been told I need to use af Chi square test with two degrees of freedom.

Can anybody tell me where I can find a calculater for this or help me in any other way.

thanks in advance for any help

Rebekka

Hi!

I think doing a Chi-Test can be pretty tricky if you don´t know statistics.
There are calculators that can do this, and software, but you still need to know how to input the data etc.

CHI-SQUARE TEST

This was something I found, it might help you.
There are plenty of resources online.

The Chi-Test is used to check wheter data contradicts the choice of a specific distribution function.

Other tests, like a deviance test, is often used for checking if different data are simply variance, or if some data actually have a different underlying distribution, or at least other parameters in the distribution function.

Thanks for your help. I'll have a look at it and see if I can figure it out.