[R] prop.trend.test issue

[Ethan Johnsons]

I don't find any other test avail for this?
Am I missing something?

thx

ej

On 12/3/06, Michael Dewey <info at aghmed.fsnet.co.uk> wrote:
> At 05:55 03/12/2006, Ethan Johnsons wrote:
> >I have the clinical study data.
> >
> >                                            Year 0       Year 3
> >Retinol (nmol/L)        N       Mean +-sd       Mean +-sd
> >Vitamin A group         73      1.89+-0.36      2.06+-0.53
> >Trace group                57      1.83+-0.31     1.78+-0.30
> >
> >where N is the number of male for the clinical study.
> >
> >I want to test if the mean serum retinol has increased over 3 years
> >among subjects in the vitamin A group.
>
> If you want to test means why did you think a test for proportions
> was a good idea?
>
>
> >>  1.89+0.36
> >[1] 2.25
> >>1.89-0.36
> >[1] 1.53
> >>2.06+0.53
> >[1] 2.59
> >>2.06-0.53
> >[1] 1.53
> >
> >
> >>prop.trend.test(c(2.25, 1.53),c( 2.59, 1.53))
> >
> >        Chi-squared Test for Trend in Proportions
> >
> >data:  c(2.25, 1.53) out of c(2.59, 1.53) ,
> >using scores: 1 2
> >X-squared = 0.2189, df = 1, p-value = 0.6399
> >
> >The issue I am seeing that N of Vitamin A group = 73 seems not reflected.
> >This leads me to think that I can't implement the test based on the
> >data just presented.
> >Nor a two-tailed test is possible.
> >
> >        2-sample test for equality of proportions with continuity correction
> >
> >data:  c(2.25, 1.53) out of c(2.59, 1.53)
> >X-squared = 0, df = 1, p-value = 1
> >alternative hypothesis: two.sided
> >95 percent confidence interval:
> >-0.6738203  0.4112720
> >sample estimates:
> >   prop 1    prop 2
> >0.8687259 1.0000000
> >
> >Warning message:
> >Chi-squared approximation may be incorrect in: prop.test(c(2.25,
> >1.53), c(2.59, 1.53))
> >
> >Any ideas, please?
> >
> >thx
> >
> >ej
> >
> >
>
> Michael Dewey
> http://www.aghmed.fsnet.co.uk
>
>