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Re: st: How to copy the contents of a variable into a new variable but in different observations


From   Sergiy Radyakin <serjradyakin@gmail.com>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   Re: st: How to copy the contents of a variable into a new variable but in different observations
Date   Tue, 22 Oct 2013 18:35:32 -0400

Clarince,

read help for the command: merge. At least it sounds to me that this
is the most relevant in your case, but I don't completely understand
your setup. Read the section 3.2 here:
http://www.stata.com/support/faqs/resources/statalist-faq/#question

I suggest: separate your data into two parts: final sample (with
potentially not all variables present, but the right number of
observations) and reference (with potentially not all observations,
but with the variables missing in the first part). Then merge first
(master) and second (using).

Your reference data may contain any attribute you want: initial price,
price in June 2000, temperature in Seattle on the day the CEO was
born, etc. But there must be a link to match the observations between
the two. If you have one record by company in the reference data (all
of the quoted examples) then the stock id should be sufficient,
otherwise consider also time variable (e.g. price on Jan 1 of the
actual year, with values of actual year differing for differing
observations).

Given the data structure you describe, you might also need the
-reshape- command. Your data appears to be in 'wide' format. You might
need to reshape it to long format, before merging.

Consider creating an example dataset that we could import to Stata to
see something similar to your data. It doesn't have to be actual
numbers, but the variables, etc. You get a much higher response rate
on your questions that way. Because not only one has to come up with
the solution to your question now, but also first to reproduce the
situation you have. Note that Stata comes with example datasets, and
more are available with the manuals, just type help datasets, perhaphs
there is already an example like your data.

Best, Sergiy Radyakin




On Tue, Oct 22, 2013 at 6:03 PM, Clarice Martins
<martins.clarice@gmail.com> wrote:
> Hello!!
>
> Can anyone help me with this?
>
> I have data that is set as stock returns for different months (variables: jun2000 jul2000 aug2000 and so on), for different companies (variable: ticker_name) and different types of returns (variable: type_return with 3 groups: "formation_period", "buy_sell_period", "holding_period")
>
> I have separated the Jun2000 returns, for the "formation period" observations, into quintile data. ie: now I have a variable called quintile that ranks from 1111 to 5555, my Jun2000 returns for the formation_period only.
>
> Now, I need to copy these quintile numbers between companies (same companies) from "formation period" observations to "buy sell period" observations.   ie.: if AMBV4 has 1 in the "formation period", i need to carry 1 to AMBV4 in the "buy_sell_period" and "hold period" observations.
>
> Is this possible? What is the best way?
>
> I am new at stata and I have been learning a lot of new things, but I am having difficulty with this... Can you guys give a hand??
>
> Thank you very much!!
> Clarice
>
>
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