Difference between revisions of "Documentation/How Tos/Calc: POISSON function"
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=== Syntax: === | === Syntax: === | ||
<tt>'''POISSON(x; λ; mode)'''</tt> | <tt>'''POISSON(x; λ; mode)'''</tt> | ||
| − | : 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>'''λ'''</tt> events are expected. <tt>'''x'''</tt> should be >=0 and <tt>'''λ'''</tt> should be >0. | + | : 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>'''λ'''</tt> events are expected. <tt>'''x'''</tt> should be >=0 and <tt>'''λ'''</tt> should be >0. <tt>'''x'''</tt> should be integer. |
: 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 22:56, 21 December 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. x should be >=0 and λ should be >0. x should be integer.
- If mode is 0, POISSON calculates the probability density function of the Poisson distribution:
- If mode is 1, POISSON calculates the cumulative distribution function of the Poisson distribution:
Example:
POISSON(8; 9; 0)
- returns approximately 0.1317, the probability that exactly 8 events occur in a time period where you expect 9 events.
POISSON(8; 9; 1)
- returns approximately 0.4556, the probability that up to and including 8 events occur in a time period where you expect 9 events.
See also:
Functions listed alphabetically, Functions listed by category
