[R] From THE R BOOK -> Warning: In eval(expr, envir, enclos) : non-integer #successes in a binomial glm!

[Corrado]

Dear friends,

I am testing glm as at page 514/515 of THE R BOOK by M.Crawley, that is 
on proportion data.

I use glm(y~x1+,family=binomial)

y is a proportion in (0,1), and x is a real number.

I get the error:

In eval(expr, envir, enclos) : non-integer #successes in a binomial glm!

But that is exactly what was suggested in the book, where there is no 
mention of a similar warning. Where am I going wrong?

Here is the output:

 > glm(response.prepared~x,data=dddd,family=binomial)

Call:  glm(formula = response.prepared ~ x, family = binomial, data = dddd)

Coefficients:
(Intercept)            x 
    -0.3603       0.4480 

Degrees of Freedom: 510554 Total (i.e. Null);  510553 Residual
Null Deviance:      24420
Residual Deviance: 23240        AIC: 700700
Warning message:
In eval(expr, envir, enclos) : non-integer #successes in a binomial glm!
 >



Regards
-- 

Corrado Topi
PhD Researcher
Global Climate Change and Biodiversity
Area 18,Department of Biology
University of York, York, YO10 5YW, UK
Phone: + 44 (0) 1904 328645, E-mail: ct529 at york.ac.uk