# OpenEpi, Version of December 2003

## Test Results for R by C Table Module

Dataset # | Data | Compared with | Result
RC1 | 983,383,2892 679,416,2625 134,84,570 | Snedecor and Cochran, Statistical Methods, Seventh ed., Iowa State, 1980, p. 210 | Agree with chi square of 40.54, p < .0000001, df=4
RC2 | 43,11 3,18 | Epi Info chi sq=27.2225 Oswego/Vanilla by Ill P=1.3505e-6 http://www.fourmilab.ch/rpkp/experiments/analysis/chiCalc.html for this chi sq value, p=1.8126e-7 RxC module gives 27.22 P=1.813e-7 | Chi Square agrees (27.22) with Epi Info, but p value for 1 d.f. differs. RbyC does agree with the p-value from the url given, however. P=0.0000001813
|  | Generated a 5 x 5 table that gave chi square of 45.5, with 16 df. P value was .0001162 and site above gave 0.0001 Generated another table with 4 d.f. chi sq 0 .4688. chiCalc gave p=0.9764, Rxc gave 0.9765. Hence the p from chi square appears to work correctly. |

By Andy Dean. Agreement is considered satisfactory if the first two significant figures agree, when a number, such as a p-value, is small.

Conclusions: R x C gives correct results for the Snedecor/Cochran 3 x 3 table. The calculation of p with 1 df differs from Epi Info, Version 3, by an order of magnitude, but agrees with p from a website in Switzerland. It may be advisable to look into Epi Info’s p-value calculator when p is very small.

R x C appears ready for use.