[R] About poisson distribution fitting and testing
spencer.graves at pdf.com
Sun Apr 23 06:04:20 CEST 2006
The easiest, general function in R that I know for fitting
distributions is "fitdistr" in library(MASS). However, for Poisson, I
might also try "glm(y~1, family = poisson, ...)". Regarding testing for
goodness of fit, I just got 44 hits for RSiteSearch("goodness of fit to
hope this helps.
p.s. My reply might have been more informative if you had provided
example data. For example, for the Poisson, the theoretical variance
equals the mean. Clearly, if the sample mean and variance are 6 and 11,
that alone could raise questions about the adequacy of the Poisson
assumption, depending on the sample size.
Linda Lei wrote:
> Hi All,
> I have a sequence of positive integers, which is right skewed. The mean
> value is 6 and variance is 11.
> I suspect it can be fitted by poisson distribution. But I'm not familiar
> with the function to fit distribution.
> Could you please help me with it? Also, once I fit the poisson
> distribution, how can I check the good-ness of this fitting?
> Thank you!
> [[alternative HTML version deleted]]
> R-help at stat.math.ethz.ch mailing list
> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
More information about the R-help