# st: RE: [Re: How to program a loop to calculate the value of an observation]

 From n j cox To statalist@hsphsun2.harvard.edu Subject st: RE: [Re: How to program a loop to calculate the value of an observation] Date Tue, 06 Feb 2007 17:43:11 +0000

```I was a bit dopey to multiply everything by 10000
and then average. That's in the formula, I was given,
but even so.

The program ended

gen double `HHI' = (100 * (`A' + `B') / `Stotal')^2
su `HHI', meanonly
}

di as txt "Schmalensee AVE_HHI " as res r(sum)
return scalar AVE_HHI = r(sum)
end

but would be better as

gen double `HHI' = ((`A' + `B') / `Stotal')^2
su `HHI', meanonly
}

di as txt "Schmalensee AVE_HHI " as res 10000 * r(sum)
return scalar AVE_HHI = 10000 * r(sum)
end

and even better without the factor 10000 altogether. The measure
is at root a probability, after all.

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

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```