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Help with CHI-SQUARE test and HYPOTHESIS

I have a clinical trail where all the patients are suffering from a stroke.

Half of the patients got drug and the other half got placebo.

I need to assess the efficacy of the drug treatment for the entire sample by using the chi-square test in excel.

I have the values if the treatment(drug/placebo) was a succes or a failure for each patient (attached file).

My quesiton is what chi-square do i need to do in order to determine which drug is better? goodness-of-fit or independence?

I think independence but im not sure...

And also if anyone can help me with the null and the alternative hypothesis, cause i have no idea what to write :\

THANKS A LOT!!!!

Re: Help with CHI-SQUARE test and HYPOTHESIS

Quote:

Originally Posted by

**eladgro** I have a clinical trail where all the patients are suffering from a stroke.

Half of the patients got drug and the other half got placebo.

I need to assess the efficacy of the drug treatment for the entire sample by using the chi-square test in excel.

I have the values if the treatment(drug/placebo) was a succes or a failure for each patient (attached file).

My quesiton is what chi-square do i need to do in order to determine which drug is better? goodness-of-fit or independence?

I think independence but im not sure...

And also if anyone can help me with the null and the alternative hypothesis, cause i have no idea what to write :\

THANKS A LOT!!!!

Hi eladgro! :)

A goodness-of-fit is when you want to know if a set of frequencies matches a known distribution.

Since you do not have a known distribution, you're not testing for goodness-of-fit.

You do want to know if treatment and result are dependent or not.

So indeed, you have a test for independence.

H0: treatment and result are independent

Ha: treatment and result are dependent

You have a p-value of 0,000000062

Typically you would test against an alpha of 0,05.

So your result is significant.

The statistical conclusion is that treatment with the drug has a significant effect on the success failure rate ($\displaystyle \chi^2(1)$, p = 0,000000062).

Re: Help with CHI-SQUARE test and HYPOTHESIS

Thank you very much!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! :)