[R] chisq.test

[Peter Dalgaard]

"Stephen Choularton" <mail at bymouth.com> writes:

> Hi
>  
> I am trying to use this function.  Can anyone show me how I would input
> the following example?
>  
> Chi-Squared = (40-30)^2 + (20-30)^2 + (30-30)^2
>                            30           30             30
>  
> = 3.333 + 3.333 + 0 = 6.666 (p value = 0.036)

> chisq.test(c(40,30,20))

        Chi-squared test for given probabilities

data:  c(40, 30, 20)
X-squared = 6.6667, df = 2, p-value = 0.03567

>  
> I want to be able to use different denominators so can you show me how I
> can do it to accommodate these rather than assuming they are all the
> same.

 No. You want to test different *hypotheses* about the distribution on
 the three groups. E.g. for 2:1:1 split:

> chisq.test(c(40,30,20),p=c(.5,.25,.25))

        Chi-squared test for given probabilities

data:  c(40, 30, 20)
X-squared = 3.3333, df = 2, p-value = 0.1889
 

-- 
   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
 (*) \(*) -- University of Copenhagen   Denmark          Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)                  FAX: (+45) 35327907