# [Scipy-tickets] [SciPy] #1401: Negative p from fisher_exact

SciPy Trac scipy-tickets@scipy....
Wed Mar 2 17:47:47 CST 2011

```#1401: Negative p from fisher_exact
--------------------------+-------------------------------------------------
Reporter:  fubar         |       Owner:  somebody
Type:  defect        |      Status:  new
Priority:  normal        |   Milestone:
Component:  scipy.stats   |     Version:  0.9.0
Keywords:  fisher_exact  |
--------------------------+-------------------------------------------------

Comment(by fubar):

In case this helps, R gives:

{{{
> fisher.test(matrix(c(17704,496,1065,77),nrow=2))

Fisher's Exact Test for Count Data

data:  matrix(c(17704, 496, 1065, 77), nrow = 2)
p-value = 1.363e-11
alternative hypothesis: true odds ratio is not equal to 1
95 percent confidence interval:
1.986867 3.314936
sample estimates:
odds ratio
2.580437

> fisher.test(matrix(c(17704,496,1065,76),nrow=2))

Fisher's Exact Test for Count Data

data:  matrix(c(17704, 496, 1065, 76), nrow = 2)
p-value = 2.666e-11
alternative hypothesis: true odds ratio is not equal to 1
95 percent confidence interval:
1.957972 3.276038
sample estimates:
odds ratio
2.546942

> fisher.test(matrix(c(17704,496,1065,75),nrow=2))

Fisher's Exact Test for Count Data

data:  matrix(c(17704, 496, 1065, 75), nrow = 2)
p-value = 5.56e-11
alternative hypothesis: true odds ratio is not equal to 1
95 percent confidence interval:
1.929286 3.237378
sample estimates:
odds ratio
2.513442

> sessionInfo()
R version 2.12.0 (2010-10-15)
Platform: x86_64-unknown-linux-gnu (64-bit)

locale:
[1] LC_CTYPE=en_AU.UTF-8       LC_NUMERIC=C
[3] LC_TIME=en_AU.UTF-8        LC_COLLATE=en_AU.UTF-8
[5] LC_MONETARY=C              LC_MESSAGES=en_AU.UTF-8
[7] LC_PAPER=en_AU.UTF-8       LC_NAME=C
[11] LC_MEASUREMENT=en_AU.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

loaded via a namespace (and not attached):
[1] tools_2.12.0
}}}

--
Ticket URL: <http://projects.scipy.org/scipy/ticket/1401#comment:1>
SciPy <http://www.scipy.org>
SciPy is open-source software for mathematics, science, and engineering.
```