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RE: st: assignment by indexing


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: assignment by indexing
Date   Wed, 4 Feb 2004 15:50:10 -0000

OK. Sometimes just spelling things out 
is clearest (and quickest in person time). 
But consider also 

quietly { 
	replace   `p1' = invlogit(`lgtp1')
	forval j = 2/13 { 
		local k = `j' - 1 
		replace   `p`j''  = `p`k''  * `ka' + (1-`p`k''  ) * `mu'
	} 
} 

Nick 
n.j.cox@durham.ac.uk 

Ben Pelzer
 
> Nick,
> 
> Your answer yesterday was clear. I was looking for a neat way 
> to solve the
> problem, but finally decided to use the following set of 
> commands for a
> similar, yet smaller, problem of only 13 timepoints:
> 
>   quietly replace   `p1' = invlogit(`lgtp1');
>   quietly replace   `p2'  = `p1'  * `ka' + (1-`p1'  ) * `mu'
>   quietly replace   `p3'  = `p2'  * `ka' + (1-`p2'  ) * `mu'
>   quietly replace   `p4'  = `p3'  * `ka' + (1-`p3'  ) * `mu'
>   quietly replace   `p5'  = `p4'  * `ka' + (1-`p4'  ) * `mu'
>   quietly replace   `p6'  = `p5'  * `ka' + (1-`p5'  ) * `mu'
>   quietly replace   `p7'  = `p6'  * `ka' + (1-`p6'  ) * `mu'
>   quietly replace   `p8'  = `p7'  * `ka' + (1-`p7'  ) * `mu'
>   quietly replace   `p9'  = `p8'  * `ka' + (1-`p8'  ) * `mu'
>   quietly replace   `p10' = `p9'  * `ka' + (1-`p9'  ) * `mu'
>   quietly replace   `p11' = `p10' * `ka' + (1-`p10' ) * `mu'
>   quietly replace   `p12' = `p11' * `ka' + (1-`p11' ) * `mu'
>   quietly replace   `p13' = `p12' * `ka' + (1-`p12' ) * `mu'
> 
> Here, ka and mu are the transition probs. Of course, following your
> matrix-suggestion would solve all problems but also cause 
> some extra work,
> while copying statements is very fast... I didn't know the 
> 'egen' statement,
> so, I'll have a look at it right away. Thanks again, Ben.

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