Joe Hilbe has used the name -cpoisson- for
two quite different programs, for cumulative
and for censored Poisson.
The first, published in STB-1, sounds closer to what
you want, but it long predates
the -poisson- command, and it is not compatible
with that. Also, it -drop-s all data in memory
without warning!!!
My guess is that your own program needs a lot of
changes before it will work. You are putting constants in variables
(not illegal, but inefficient) and variables in constants
(usually fatal). The line
local cum = `cum' = ((exp(-poi_pred)*(poi_pred^`i'))/`fact')
even after correcting the second = to + is not
going to work the way you want it to.
I recommend keeping much closer to what -predict-
can supply for you.
Nick
[email protected]
Patrick McElduff
> Hi Nick
>
> What I am attempting to do (and there may be a much more
> simple solution) is to calculate the exact probability of
> observing a value of x or greater given that I expect to
> observe mu. The value of mu comes from a poisson regression
> and is potentially different for each observed value.
>
> The code that I believe works is:
>
> generate temp = 0
>
> local i = 0
> local cum = 0
> generate prob = 0
>
> while `i' <= cases {
> local j = 1
> local fact = 1
>
> while `j' <= `i' {
> local fact = `fact' * `j'
> local j = `j' + 1
> }
>
> local cum = `cum' = ((exp(-poi_pred)*(poi_pred^`i'))/`fact')
> local i = `i' + 1
> replace prob = 1 - `cum' if `i' == cases & cases ~= 0
> replace prob = 1 if cases == 0
> }
>
> There is also a program called cpoisson by Joseph Hilbe that
> can by easily modified to work for my scenario but it doesn't
> seem to return the answer the way I need it to.
> >>> [email protected] 21/12/2005 8:46:33 am >>>
> You can't write a program with exactly
> this syntax. You could write an -egen-
> function.
>
> If you want a new variable as output,
> why this question?
>
> I could start speculating on what you might mean,
> but better that you should tell us much more.
>
> Indeed, please show us your program.
>
> Nick
> [email protected]
>
> Patrick McElduff
>
> > I want to write a program that has two arguements and
> > returns a value so that I can use it in the form:
> >
> > generate temp = program(var1 var2)
> >
> > I have written the guts of the program to do the work but I
> > don't know how to get the input and output in the form I want.
> >
> > Could you please tell me where I should start looking.
>
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