[R] Is there dpois equivalent for zero-inflated Poisson?

Thierry Onkelinx thierry.onkelinx at inbo.be
Tue Mar 22 13:17:25 CET 2016

Dear Matti,

What about this?

dzeroinflpois <- function(x, lambda, zero){
  ifelse(x == 0, zero, 0) + dpois(x, lambda) / (1 - zero)
plot(x, dzeroinflpois(x, lambda = 10, zero = 0.2), type = "l")

ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature and
team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance
Kliniekstraat 25
1070 Anderlecht

To call in the statistician after the experiment is done may be no more
than asking him to perform a post-mortem examination: he may be able to say
what the experiment died of. ~ Sir Ronald Aylmer Fisher
The plural of anecdote is not data. ~ Roger Brinner
The combination of some data and an aching desire for an answer does not
ensure that a reasonable answer can be extracted from a given body of data.
~ John Tukey

2016-03-22 13:04 GMT+01:00 Matti Viljamaa <mviljamaa op kapsi.fi>:

> I’m doing some optimisation that I first did with normal Poisson (only
> parameter theta was estimated), but now I’m doing the same with a
> zero-inflated Poisson model which
> gives me two estimated parameters theta and p (p is also pi in some
> notation).
> My question is, is there something equivalent to dpois that would use both
> of the parameters (or is the p parameter possibly unnecessary)?
> I’m calculating the “fit” of the Poisson model
> i.e. like
> x = c(0,1,2,3,4,5,6)
> y = c(3062,587,284,103,33,4,2)
> fit1 <- sum(y)*dpois(x, est_theta)
> and then comparing fit1 to the real observations.
>         [[alternative HTML version deleted]]
> ______________________________________________
> R-help op r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

	[[alternative HTML version deleted]]

More information about the R-help mailing list