Difference between revisions of "Documentation/How Tos/Calc: POISSON function"

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=== Syntax: ===
 
=== Syntax: ===
 
<tt>'''POISSON(x; &lambda;; mode)'''</tt>
 
<tt>'''POISSON(x; &lambda;; mode)'''</tt>
: The Poisson distribution is a discrete probability distribution giving the probability that a <tt>'''x'''</tt> events occur in a certain time, where events occur independently, and where on average <tt>'''&lambda;'''</tt> events are expected.
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: The Poisson distribution is a discrete probability distribution giving the probability that <tt>'''x'''</tt> events occur in a certain time, where events occur independently, and where on average <tt>'''&lambda;'''</tt> events are expected.
  
 
: If mode is <tt>'''0'''</tt>, <tt>'''POISSON'''</tt> calculates the probability density function of the Poisson distribution:
 
: If mode is <tt>'''0'''</tt>, <tt>'''POISSON'''</tt> calculates the probability density function of the Poisson distribution:

Revision as of 18:03, 19 May 2008


POISSON

Calculates values for a Poisson distribution.

Syntax:

POISSON(x; λ; mode)

The Poisson distribution is a discrete probability distribution giving the probability that x events occur in a certain time, where events occur independently, and where on average λ events are expected.
If mode is 0, POISSON calculates the probability density function of the Poisson distribution:
Calc poisson0 equation.png
If mode is 1, POISSON calculates the cumulative distribution function of the Poisson distribution:
Calc poisson1 equation.png

Example:

POISSON(8; 9; 0)

returns approximately 0.1317, the probablity that exactly 8 events occur in a time period where you expect 9 events.

POISSON(8; 9; 1)

returns approximately 0.4556, the probablity that up to and including 8 events occur in a time period where you expect 9 events.

See also:

Statistical functions

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