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From |
Dan Waldo <dan_waldo@yahoo.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: using vector notation to simplify coding |

Date |
Fri, 14 Aug 2009 06:13:53 -0700 (PDT) |

Thanks for the suggestion, Austin. Reshaping is a good idea, although I am not sure how I'd implement that in my particular case: each record has 6 monthly figures (ing_1 through ing_6) but the months they're drawn from (mes_1 through mes_6) are not the same for all records. It's helpful to know that each record's months are sequential. So, one semi-hard-code method would be to create a small dataset containing a record for each possible value of mes_1 (in this case, July through October); the record would have mes_1 and def_1 though def_6, the latter being the appropriate months' deflators. Then this file is merged onto the base file: . clear . input mes_1 def_1-def_6 1. 7 1.07 1.06 1.05 1.04 1.03 1.02 2. 8 1.08 1.07 1.06 1.05 1.04 1.03 3. 9 1.09 1.08 1.07 1.06 1.05 1.04 4. 10 1.10 1.09 1.08 1.07 1.06 1.05 5. end . save def , replace . use ingresos , clear . merge mes_1 using def , sort uniqus . drop if _merge==2 . gen ding_1=100*ing_1/def_1 . gen ding_2=100*ing_2/def_2 etc . drop def_1-def_6 It's clunky but gets the job done. But it's not generalizable ... and the other solutions offered are. Dan --- On Wed, 8/12/09, Austin Nichols <austinnichols@gmail.com> wrote: > From: Austin Nichols <austinnichols@gmail.com> > Subject: Re: st: using vector notation to simplify coding > To: statalist@hsphsun2.harvard.edu > Date: Wednesday, August 12, 2009, 11:18 AM > Dan-- > This is really more a data structure issue--you will save > yourself a > lot of trouble in the long run by reorganizing the data, > for example > by making it "long" format for panel regressions (help > reshape). If > you have month and year on the data, you can -merge- to get > a cpi > variable and deflate with a line like: > g realy=y/cpi > and see also -cpigen- on SSC. > > On Wed, Aug 12, 2009 at 11:12 AM, Kit Baum<baum@bc.edu> > wrote: > > <> > > Dan said > > > > Thanks for the clarification, Kit. I am having trouble > shaking the SAS > > mindset on this stuff, and your note, along with > Michael's, have helped a > > lot. I "get" the mata approach, being a old Fortran > guy ...it feels like a > > cumbersome solution in Stata right now, but I am sure > that is a transitory > > feeling. > > > > Actually it is a very elegant solution, taking > advantage of the concept of > > 'view matrices' in Stata. Surely as another old > Fortran guy you remember the > > EQUIVALENCE statement. That's what is happening with a > view matrix (real > > programmers don't need no steenken pointers!) so that > changes in Mata to the > > contents of the matrix (Y in my code) actually changes > the contents of the > > Stata variables that populate the matrix. That is very > powerful (and > > naturally can be dangerous if misunderstood). > > > > See http://ideas.repec.org/p/boc/dsug09/06.html > > (and ITSP, which illustrates this at greater length) > > > > Cheers > > Kit > > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ > * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: using vector notation to simplify coding***From:*Austin Nichols <austinnichols@gmail.com>

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