# 95% confidence interval for the difference in true proportions for Chi-squared test

#### cewylie

##### New Member
Hello,

Apologies if this has been covered, but if so I couldn't find it. Can anyone please tell me how to calculate the 95% confidence interval for the difference in true proportions for Chi-squared test (not for the Odds Ratio).

I can work it out manually (I know it should be 0.082 to 0.524), but I can't get R to produce the output.

2x2 table

Disease RF positive RF negative Total
With disease 21 13 34
Without disease 12 26 38
Total 33 39 72

I am currently calculating the Chi-squared by:

CrossTable(MPATable, fisher=TRUE, chisq=TRUE, expected=TRUE, sresid=TRUE,format='SPSS') which generates:

Chi^2 = 5.426227 d.f. = 1 p = 0.01983649

On the assumption the answer might be the same...I would also be very grateful for the same advice in relation to the 95% confidence interval for the true difference in the true proportion for McNemar's test for Paired data.

Thanks in advance 