so, so we can calculate a standard error for the log

odds ratio that works out to be an incredibly convenient formula.

It's the square root of 1 over all the cell counts added up.

So 1 over

n 1 1, plus 1 over n 1 2, plus 1 over n

2 1, plus 1 over n 2 2, square root of the whole thing.

So you shouldn't forget the standard error of

the log odds ratio, because it's super easy.

So again, to create a confidence interval for

the population odds ratio, you calculate the odds ratio.

Show.

Log it.

Calculate the standard error of the log odds ratio.

Add or subtract a standard normal quantile say 1.96 if you wanted

a 95% confidence interval to your log odds ratio.

And that will give you an interval estimate for the log odds ratio.

Exponentiate the end points and that gives

you an interval estimate for the odds ratio.

Now, again we have a little bit of a problem if n 1 2 or n 2 1 is 0.

and there's some fixes for that often

involving adding small amounts to every cell is

a, is a, is a common fix.

Okay so some comments about the odds ratio.

So one interesting fact is if you, notice if you