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Re: st: Re: creating average over past three years within groups


From   "Martin Weiss" <[email protected]>
To   <[email protected]>
Subject   Re: st: Re: creating average over past three years within groups
Date   Fri, 3 Oct 2008 15:10:45 +0200

Well, no, if you -sum, meanonly- your medians then it delivers the mean of medians. The problem with your proposal is that the -local- assignment does not allow an -if- statement. That is why I say: calculate your results beforehand with -sum- and the -if- statement, store them in -local-s and then do your -replace-...

HTH
Martin
_______________________
----- Original Message ----- From: "Fabian Brenner" <[email protected]>
To: <[email protected]>
Sent: Friday, October 03, 2008 3:04 PM
Subject: Re: st: Re: creating average over past three years within groups



Dear Martin:

your proposal will result in the 3-year-mean of means; but I want to get the 3-year-mean of (yearly) medians (across observations). This is why I cannot use meanonly; I would need "medianonly" for your solution, which unfortunately doesn't exist.

Please correct me if I'm wrong.

This is why I want to do it like this, but I don't kow what is wrong (Stata says: if not allowed r(101))

quietly forvalues k = 1/10 {
quietly forvalues y = 1974/2000 {
local median3 = oneyearmedian if year == `= `y' - 3' & industry == `k',
local median2 = oneyearmedian if year == `= `y' - 2' & industry == `k',
local median1 = oneyearmedian if year == `= `y' - 1' & industry == `k',
replace fiveyearmedian = (`median3' + `median2' + `median1' ) / 3 if year == `y' & group == `k'
}
}

Hope someone could tell me..Thanks.


-------- Original-Nachricht --------

Datum: Fri, 3 Oct 2008 14:52:12 +0200
Von: "Martin Weiss" <[email protected]>
An: [email protected]
Betreff: Re: st: Re: creating average over past three years within groups

True, consecutive -summarize-s will overwrite the rclass results so you
have
to store the r(mean) them in -local-s. Apart from that, I do not know what
is wrong with my proposal...

HTH
Martin
_______________________
----- Original Message ----- From: "Fabian Brenner" <[email protected]>
To: <[email protected]>
Sent: Friday, October 03, 2008 2:40 PM
Subject: Re: st: Re: creating average over past three years within groups


> Dear Martin,
>
> I don't know if I got what you mean, but as far as I know your proposal
> using -summarize, meanonly- would lead to the average (across the most
> recent three years) of the mean (across observations within each year).
>
> But I want to get the average (across the most recent three years) of
the
> median (across observations within each year), i.e.
> average1997=(median1997+median1996+median1995)/3
>
> Hope someone could help me.
> Fabian
>
>
> [I guess your proposal would look like the following:
> quietly forvalues k = 1/10 {
> quietly forvalues y = 1974/2000 {
> summarize age if year == `= `y' - 3' & group == `k', meanonly
> local median3 = r(mean)
> summarize roe if year == `= `y' - 2' & group == `k', meanonly
> local median2 = r(mean)
> summarize roe if year == `= `y' - 1' & industry == `k', meanonly
> replace fiveyearmedian = (`median3' + `median2' + r(mean1 ) / 3 if year
==
> `y' & group == `k'
> }
> }
>
>
>
> -------- Original-Nachricht --------
>> Datum: Fri, 3 Oct 2008 14:22:16 +0200
>> Von: "Martin Weiss" <[email protected]>
>> An: [email protected]
>> Betreff: st: Re: creating average over past three years within groups
>
>> Not sure what you are doing with all those -locals-. Just -summarize,
>> meanonly- with your -if- statements and type -ret li- afterwards. >> There
>> you
>> will find the average as r(mean) to plug into your -replace- >> operation.
>>
>> HTH
>
>> Martin
>> _______________________
>> ----- Original Message ----- >> From: "Fabian Brenner" <[email protected]>
>> To: <[email protected]>
>> Sent: Friday, October 03, 2008 2:17 PM
>> Subject: st: creating average over past three years within groups
>>
>>
>> > Dear all:
>> >
>> > I used -bysort year group : egen oneyearmedian = median(age)- to
create
>> > the median within each group (1-10) for each year (1974-2000).
>> >
>> > Now I want to get the three year average of the three median for >> > each
>> > group for the most recent three years:
>> >
>> > generate threeyearaverage = .
>> > sort year group
>> >
>> > quietly forvalues k = 1/10 {
>> > quietly forvalues y = 1974/2000 {
>> > local median3 = oneyearmedian if year == `= `y' - 3' & industry ==
`k',
>> > local median2 = oneyearmedian if year == `= `y' - 2' & industry ==
`k',
>> > local median1 = oneyearmedian if year == `= `y' - 1' & industry ==
`k',
>> > replace fiveyearmedian = (`median3' + `median2' + `median1' ) / 3 if
>> year
>> > == `y' & group == `k'
>> > }
>> > }
>> >
>> > But stata always says: if not allowed r(101);
>> >
>> > What do I wrong? Hope someone can help me.
>> > Fabian Brenner
>> >
>> >
>> > -- >> > GMX startet ShortView.de. Hier findest Du Leute mit Deinen
Interessen!
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>>
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>
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