# I Understanding Yates' correction

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1. Feb 9, 2017

### Tyto alba

I was studying Biostatistics by Zar, the Yates' correction part and stumbled upon this:

My doubts:

1. The conculsions are not taking place exactly at the level of alpha- what does this mean?
Do the values of Chi square mentioned in table not correspond to the alpha(probability) indicated? Is the corresponding value actually a range?

1. I also don't understand what it means by 'This situation would be unfortunate were it not for the fact that the approximation is a very good one, except when df=1. In the case of df=1, it is usually recommended to use Yates correction for continuity.'
Why is Yates' correction specifically done when df=1?

Last edited: Feb 9, 2017
2. Feb 9, 2017

### MarneMath

The statistics for the table simply do not have a chi squared distribution. We have a fixed count and hence a discrete distribution whereas the chi-squared is continuous. Nevertheless the chi-squared distribution is a reasonable approximation for the contingency table. I don't agree that you should use Yates correction when the degrees of freedom is one. I argue that you should never use Yates correction.