I have one observation by person. I one dataset I have personal
chracteristics and in the other laboral variables.
SEbas.
2008/3/11, Vladimir Vakhitov <[email protected]>:
> It depends on what you would like to get at the end. The first
> question is "what does uniquely identifies your observations?" What is
> an observation, then?
>
> -Merge- is used when you want to add some extra characteristics to
> your observations (for example, add a region characteristics to each
> observation based on its region ID).
> -standby- forms a set of all possible intersections, kinda like INNER
> JOIN in Access. Sometimes you don't want this because you get too many
> messy intersections.
>
>
>
> Volodymyr
>
>
> 2008/3/11, Sebastian Kruk <[email protected]>:
> > Dear statalist users,
> >
> >
> > I have two dataset, A and B.
> >
> > A) number, sex, age, citizen
> >
> > B) number, sex, civil status, children
> >
> > I have to form a new dataset but number and sex do not uniquely
> > identify observations.
> > Number of observacions of A can be >,< or = Number of observations of B.
> >
> > What's better, merge or joinby?
> >
> > Bye,
> >
> > Sebastian.
> >
> > 2008/3/5, Nick Cox <[email protected]>:
> > > Two minute comments only:
> > >
> > > local assets=qassets
> > >
> > > this looks wrong: qassets[`i'] ?
> > >
> > > quietly:use compustat if `qtr'=obsqtr & `sic'=sic3 &
> > > qsales<=1.15*`sales'/*
> > > */ &
> > > qsales>=.85*`sales'&qassets<=1.2*`assets'&qassets>=.85*`assets', clear
> > >
> > > tests for equality are ==, not =
> > >
> > > Malcolm Wardlaw
> > >
> > > I wanted to pose this question to Statalist regarding matching data to a
> > >
> > > range of values instead of exact values. I kind of asked this question
> > > before, but I realized from the response that my question was somewhat
> > > ill formed, so I'll try to be as explicit as possible. I will use an
> > > example to illustrate the question.
> > >
> > > Let's say I want to do a long-run event study on the changes in real
> > > growth of companies. In order to do this, I need to appropriately match
> > >
> > > the company I am running the event study on to a group of comparable
> > > companies. For this, I need a matched dataset of all companies that
> > > match in a range of accounting variables.
> > >
> > > The match occurs as follows. I have a data set (1) containing all of
> > > the companies I wish to perform the event study on. I need to then
> > > create a dataset (2) that contains matching companies from a dataset of
> > > the larger Compustat universe of all firms (3). To do this, I need to
> > > gather all firms that have the same SIC code, sales that are between 15%
> > >
> > > and -15% of the event company, and assets that are between 20% and -20%
> > > of the event company in the quarter of the event. The new dataset must
> > > also have a marker for each of these group of sample firms that
> > > corresponds to the event firm.
> > >
> > > Here is how I originally dealt with the problem. In the program, Stata
> > > is continually cycling through the data, loading part of another dataset
> > >
> > > into memory, appending it to another dataset from disk, saving that
> > > dataset to disk, and then reloading the original dataset from disk each
> > > time. It works, but it seems very inefficient.
> > >
> > > Is there a best practice on how to do this, or is this basically as good
> > >
> > > as it's going to get?
> > >
> > > ---------------------------------------
> > > local num = _N
> > > forval i = 1/`num' {
> > > /*The sales of Event Company i*/
> > > local sales=sales[`i']
> > > /*The quarter of the observation*/
> > > local qtr=eventquarter[`i']
> > > /*SIC code*/
> > > local sic=sic3[`i']
> > > /*Assets of the event company*/
> > > local assets=qassets
> > > /*A code that uniquely tags the event*/
> > > local code=code[`i']
> > > quietly:use compustat if `qtr'=obsqtr & `sic'=sic3 &
> > > qsales<=1.15*`sales'/*
> > > */ &
> > > qsales>=.85*`sales'&qassets<=1.2*`assets'&qassets>=.85*`assets', clear
> > > gen code=`code'
> > > append using comparables
> > > quietly:save comparables,replace
> > > use events
> > > }
> > >
> > > *
> > > * For searches and help try:
> > > * http://www.stata.com/support/faqs/res/findit.html
> > > * http://www.stata.com/support/statalist/faq
> > > * http://www.ats.ucla.edu/stat/stata/
> > >
> > *
> > * For searches and help try:
> > * http://www.stata.com/support/faqs/res/findit.html
> > * http://www.stata.com/support/statalist/faq
> > * http://www.ats.ucla.edu/stat/stata/
> >
>
>
> --
> __________________
> Volodymyr Vakhitov
> [email protected]
> *
> * For searches and help try:
> * http://www.stata.com/support/faqs/res/findit.html
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
