[R] ppois

Ethan Johnsons ethan.johnsons at gmail.com
Wed Sep 20 22:01:29 CEST 2006

A quick question!

The number of episodes per year of otitis media follows a Possion
distribution with lambda = 1.6 episodes per year.   Wouldn't the
probability of getting 3 or more episodes of otitis media in the first
2 years of life be:

> ppois(q=3, lambda=1.6*2, lower.tail = TRUE, log.p = FALSE)
[1] 0.6025197

I am confused with the lambda and 3 or more..

thx much

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