{smcl}
{* 7feb2006}{...}
{hline}
help for {hi:cupoissoni}{right:(SJ6-1: sg2_1; STB-1: sg2)}
{hline}

{title:Cumulative Poisson probability calculation}

{p 8 17 2}
{cmd:cupoissoni} {it:#population_ratio} {it:#total_observations} {it:#cases}

{p 8 17 2}
{cmd:cupoissoni} {it:#population_mean} {it:#cases}


{title:Description}

{p 4 4 2}Suppose X is Poisson distributed with mean mu. Then {cmd:cupoissoni}
returns pr(X >= x) given mu and x. There are two syntaxes. You specify first
the mean mu either as the population ratio and the total number of
observations, or directly as one number; and then the number of cases x. 
 
{p 4 4 2}{cmd:cupoissoni} is an immediate command. For more on immediate
commands, see help on {help immediate}. 
 
{p 4 4 2}{cmd:cupoissoni} was originally called {cmd:cpoisson}. 
 
 
{title:Example}

{p 4 4 2}Suppose that the overall 1990 hospital mortality ratio for Arizona,
i.e. the number of deaths divided by the number of admissions, was .03 or 3%.
(It wasn't really.) You wish to determine the cumulative Poisson probability
for 20 deaths occurring in 1990 at St. Nobody Hospital in Elsewhere, AZ. Its
total admissions for the year were 845. Type
 
{p 4 8 2}{cmd:. cupoissoni .03 845 20}        

{p 4 4 2}The result is

{p 4 8 2}{txt:Cumulative Poisson probability}{res: .88035984}

{p 4 4 2}You would get the same result with 

{p 4 8 2}{cmd:. cupoissoni 25.35 20}        


{title:Saved results} 

{p 4 4 2}r(prob){space 5}cumulative probability 


{title:Author}

{p 4 4 2}Joseph Hilbe, Arizona State University{break} 
	 hilbe@asu.edu

	 
{title:Acknowledgment}

{p 4 4 2}Nicholas J. Cox helped with this update. 


{title:Also see}

{p 4 13 2}
Online:  {helpb expoissoni}
{p_end}
