Stack Overflow
Stack Overflow

Questions tagged [poisson]

The Poisson distribution is a statistical discrete distribution for describing events occurring at random intervals. It is defined on the non-negative integers that has the property in which the mean is equal to the variance.

The Poisson probability distribution is used to model the probability of a number of events occurring during a specified time interval.

The Poisson distribution is characterized by an expected arrival rate, usually designated by the Greek lower-case letter lambda.

A discrete random variable X has a Poisson distribution indexed by a parameter λ if it has probability mass function as following:

enter image description here

Useful links:

Wikipedia entry for the Poisson distribution.

How do I generate discrete random events with a Poisson distribution?

699 questions
4
votes
1 answer

rpois generates NA with large means (lambda) in R

I am debugging a larger set of nested models that only run into problems during optimization. During the process of zeroing on what I believe is causing the errors I've come across unusual behavior in the rpois() function. It seems that with very…
user3658540
  • 41
  • 2
4
votes
1 answer

Add simulated poisson distributions to a ggplot

I have made a poisson regression and then visualised the model: library(ggplot2) year <- 1990:2010 count <- c(29, 8, 13, 3, 20, 14, 18, 15, 10, 19, 17, 18, 24, 47, 52, 24, 25, 24, 31, 56, 48) df <- data.frame(year, count) my_glm <- glm(count ~ year,…
luciano
  • 13,158
  • 36
  • 90
  • 130
4
votes
1 answer

Discrete probability distribution calculation in Matlab

I have given P(x1...n) discrete independent probability values which represent for example the possibility of happening X. I want a universal code for the question: With which probability does happening X occur at the same time 0-n times? For…
Clemens
  • 245
  • 1
  • 7
4
votes
0 answers

Modelling for soccer scores (Dixon & Cole)

In Dixon, Coles (1997), they have used the maximum likelihood estimation for the two modified independent Poisson models in (4.3) to model the scores in soccer. I am trying to use R in order to "reproduce" the alpha and beta as well as the home…
Hann
  • 63
  • 5
4
votes
2 answers

Prediction intervals for poisson regression on R

I've tryed both the approaches but I find difficulties with both.. I try to explain better which is my problem before I tell you my questions with the two approaches. I have the dataset "acceptances" in which I have the number of acceptances for…
klair
  • 41
  • 1
  • 3
4
votes
1 answer

how to use predict()

Want to predict a value but this is clearly not the solution. I am doing a multiple choice test and 0.304... is not an answer.How to use predict() correctly? library(glm2) data(crabs) fit= glm(Satellites~Width,data=crabs,…
Roland Kofler
  • 1,332
  • 1
  • 16
  • 33
3
votes
2 answers

Poisson arrival distribution function and keep track it

I am trying to create a random "hello world" function based on the poisson arrival. In the code below, I define that the average mean (Lamda) is 5. And I want the time to elapse from 1 - 5 second, and keep track of it. Based on an opensource…
xambo
  • 399
  • 2
  • 4
  • 17
3
votes
0 answers

The RMSE from the train() function in the caret package gives a much different value when I use the RMSE() function from the caret package

I am trying to do model selection and want to retrieve mean RMSE from 10-fold cross validation. for some models it is possible to use the train() function from the caret package, however for other models I want to look at I have found a manual way…
EllyJ
  • 31
  • 1
3
votes
2 answers

Modifying SIR model to include stochasticity

I am trying to establish a method of estimating infectious disease parameters by comparing real epidemic curves with simulations of a stochastic SIR model. To construct the stochastic SIR model, I am using the deSolve package and instead of using…
fil0607
  • 101
  • 5
3
votes
1 answer

Graph of empirical and theoretical distributions for Zero Inflated Poisson Distribution

Following is a kind of data set I am working on it: data <- c(0, 1, 0, 11, 2, 0, 3, 0, 0, 2, 1, 3, 1, 0, 1, 0, 0, 0, 2, 3, 0, 0, 0, 8, 1, 1, 1, 0, 1, 1, 2, 7, 0, 0, 0, 5, 2, 3, 6, 1, 1, 5, 2, 9, 0, 0, 1, 21, 16, 2, 9, 6, 25, 2, 1, 12, 16, 14, 15,…
Nawa Raj
  • 111
  • 1
  • 7
3
votes
1 answer

Problem to fit a poisson histogram in python

I'm trying to fit some data with a poisson distribution, but it doesn't work. x =…
Luis Fernando Dos Prazeres
  • 69
  • 2
3
votes
0 answers

My rootogram is displaying incorrect values along the x-axis

I am trying to model the relationship between conspecific and heterospecific pollen counts on individual flowers under a poisson or negative binomial distribution using the glm()/glm.nb() functions in R…
Arjan Engelen
  • 31
  • 4
3
votes
1 answer

Is there an easier way to use scipy.stats.poisson than my current method?

I was using scipy.stats to calculate the poisson probability distribution of goals in different football matches, but I can't help but think that there's an easier way to do this. Say I am trying to calculate the probability of a game having less…
Gent Bajko
  • 78
  • 1
  • 5
3
votes
1 answer

Combining Perlin Noise and Poisson Disc Sampling in Python

I am attempting to replicate realistic vegetation placement on a 2d grid. To accomplish this I am using poisson disc sampling (Bridson algorithm) vegetation placement and perlin noise to determine density of vegetation per area. When I exclude…
Kevin Alvarez
  • 311
  • 2
  • 15
3
votes
2 answers

Manually simulating Poisson Process in R

The following problem tells us to generate a Poisson process step by step from ρ (inter-arrival time), and τ (arrival time). One of the theoretical results presented in the lectures gives the following direct method for simulating Poisson…
user366312
  • 16,949
  • 65
  • 235
  • 452
1 2 3
…
46 47