Poisson distribution (rv)

[drfg2008]

A question to the Poisson distribution: I would like to generate a poisson distributed random variable with SPSS (1). I know that the distribution is a Poisson distribution with the arithmetic mean of 5.294693 and the median of 5. What do I have to give SPSS as "mean": the median or the arithmetic mean. Or neither. In other words, what is the estimated location parameter in a Poisson distribution.

Thanks


(1)
COMPUTE rv_poisson=RV.POISSON(xyz).
EXECUTE.

[Spousta Jan]

Hi Frank,

Use the mean (5.294693). That is the lambda in the distribution formula. http://en.wikipedia.org/wiki/Poisson_distribution

Best regards

Jan


-----Original Message-----
From: SPSSX(r) Discussion [mailto:[hidden email]] On Behalf Of drfg2008
Sent: Monday, November 21, 2011 11:55 AM
To: [hidden email]
Subject: Poisson distribution (rv)

A question to the Poisson distribution: I would like to generate a poisson distributed random variable with SPSS (1). I know that the distribution is a Poisson distribution with the arithmetic mean of 5.294693 and the median of 5. What do I have to give SPSS as "mean": the median or the arithmetic mean.
Or neither. In other words, what is the estimated location parameter in a Poisson distribution.

Thanks


(1)
COMPUTE rv_poisson=RV.POISSON(xyz).
EXECUTE.

-----
Dr. Frank Gaeth
FU-Berlin

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[drfg2008]

Thanks, Jan

the arithm. mean is the lambda in the distribution formula, I under stood.

Frank

[Art Kendall]

The arithmetic mean.  A common test to see whether an empirical distribution is poisson is to see if the variance is approximately equal to the mean.

However, for many practical purposes it would not make a difference which you used.
Open a new instance of SPSS.  Paste the syntax below into a syntax window. Run it.

Art Kendall
Social Research Consultants

INPUT PROGRAM.
   LOOP id=1 TO 300000.
      COMPUTE usingmean = rv.poisson( 5.294693).
      COMPUTE usingmedian = rv.poisson( 5).
      END CASE.
   END LOOP.
   END FILE.
END INPUT PROGRAM.
FORMATS id (F3.0) usingmean usingmedian (f3).
FREQUENCIES VARS= usingmean usingmedian/statistics = mean variance.

On 11/21/2011 5:55 AM, drfg2008 wrote:

A question to the Poisson distribution: I would like to generate a poisson
distributed random variable with SPSS (1). I know that the distribution is a
Poisson distribution with the arithmetic mean of 5.294693 and the median of
5. What do I have to give SPSS as "mean": the median or the arithmetic mean.
Or neither. In other words, what is the estimated location parameter in a
Poisson distribution.

Thanks


(1)
COMPUTE rv_poisson=RV.POISSON(xyz).
EXECUTE.

-----
Dr. Frank Gaeth
FU-Berlin

--
View this message in context: http://spssx-discussion.1045642.n5.nabble.com/Poisson-distribution-rv-tp5010174p5010174.html
Sent from the SPSSX Discussion mailing list archive at Nabble.com.

=====================
To manage your subscription to SPSSX-L, send a message to
[hidden email] (not to SPSSX-L), with no body text except the
command. To leave the list, send the command
SIGNOFF SPSSX-L
For a list of commands to manage subscriptions, send the command
INFO REFCARD

===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD