Question on Poisson distrbution

Ag — Thu, 02 Apr 2009 15:25:04 +0000

Dear people,

I am working with random variables and I want to generate random values with a Poisson distribution whose ranges are between 0.8 and 1 and with a mean distribution of 5.

I have tried the following line (10 values vector) but I am not sure if I it is the right line....

a=0.8 + (1-0.8) * poissrnd(5,1,10)

Can somebody tell me if I am commiting a mistake?

Thanks a lot for the help!!!

Ag

Re: Question on Poisson distrbution

Roger Stafford — Thu, 02 Apr 2009 15:57:01 +0000

"Ag" <ag@gmail.com> wrote in message <gr2lcg$kg7$1@fred.mathworks.com>...
> .....
> I am working with random variables and I want to generate random values with a Poisson distribution whose ranges are between 0.8 and 1 and with a mean distribution of 5.
> ......
> a=0.8 + (1-0.8) * poissrnd(5,1,10)
> ......

  I believe you are confusing the notions of matlab's 'rand' function with those of 'poissrnd'. The output of 'rand' is essentially a continuous, uniform distribution on the interval [0,1], and when you write

x = a + (b-a)*rand

you get a uniform distribution over the interval [a,b].

  No such result can be obtained from 'poissrnd' using such a computation. In the first place the poisson distribution is discrete with integer values, and in the second place it is unbounded. Like normal distributions, there is no limit to its possible size. The 'a' in your computation could very easily extend far beyond the interval [.8,1].

  You need to rethink what it is you wish to achieve.

Roger Stafford

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Question on Poisson distrbution

Re: Question on Poisson distrbution