[R] epi.2by2

[peter dalgaard]

On May 17, 2011, at 12:57 , pcc wrote:

> This is a really simple question, I'm sure,but I can't make EpiR work! 
> I keep getting the following: 
> 
>> epi.2by2(47, 263483, 282, 935028, method="cohort.time", conf.level=0.95)
> Error in epi.2by2(47, 263483, 282, 935028, method = "cohort.time",
> conf.level = 0.95) : 
>  unused argument(s) (935028)
> 
> and I really don't know why!. Any ideas very very welcome
> thank you

If all else fails, try reading the manual.... For the right version, mind you.

Apparently, the formal arguments got changed so that it is now

> args(epi.2by2)
function (dat, method = "cohort.count", conf.level = 0.95, units = 100, 
    verbose = FALSE) 
NULL

with dat an 'object of class "table"'. It seems that a simple matrix will do, though:

> epi.2by2(matrix(c(47, 263483, 282, 935028),2), method="cohort.time", conf.level=0.95)
             Disease +    Time at risk        Inc rate *
Exposed +           47             282              16.7
Exposed -       263483          935028              28.2
Total           263530          935310              28.2

Point estimates and 95 % CIs:
---------------------------------------------------------
Inc rate ratio                           0.59 (0.43, 0.79)
Attrib rate *                            -11.51 (-16.28, -6.75)
Attrib rate in population *              0 (-0.16, 0.15)
Attrib fraction in exposed (%)           -69.07 (-130.11, -27.14)
Attrib fraction in population (%)        -0.01 (-0.01, -0.01)
---------------------------------------------------------
 * Cases per 100 units of population time at risk 

(presumably you really want the transpose)

-- 
Peter Dalgaard
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com