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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
st: RE: AW: RE: Re: Generate Variable |

Date |
Thu, 12 Mar 2009 13:26:19 -0000 |

In Martin's second last line: bys id: g byte higher83=`inc83'>`inc80' The -bys id- does no harm, but is unnecessary. More importantly, he raises a good question about missings. Here's a better approach if missings are present: egen numProp4 = mean(numProp) if wavenum == 4, by(id) bysort id (numProp4) : replace numProp4 = numProp4[1] egen numInsArrng6 = mean(numInsArrng) if wavenum == 6, by(id) bysort id (numInsArrng6) : replace numInsArrng6 = numInsArrng6[1] gen myindicator = numProp4 < numInsArrng6 if !missing(numProp4, numInsArrng6) (Note incidentally that Martin's original code assumes that each year of interest is represented in each panel, and will give incorrect results if either year is omitted.) Nick n.j.cox@durham.ac.uk Martin Weiss That is a superior solution to mine, and I recommend that Erick should use this one. Here is an adaption to my dataset, checking for an income gain between 80 and 83: ************* clear* inp id year sex inc 1 80 0 5000 1 81 0 5500 1 82 0 6000 1 83 0 7000 2 80 1 2000 2 81 1 2200 2 82 1 3300 2 83 1 3500 3 80 0 3000 3 81 0 2000 3 82 0 1000 3 83 0 1000 4 80 0 3000 4 81 0 4000 4 82 0 1000 4 83 0 10000 end tempvar inc80 inc83 egen `inc80' = total((year == 80) * inc) , by(id) egen `inc83' = total((year == 83) * inc) , by(id) bys id: g byte higher83=`inc83'>`inc80' l, noo sepby(id) As always, be advised that missings count as arbitrarily large, so you want to be extra careful and double-check any results... Nick Cox Another approach: I infer panel structure with an identifier, and at most one measurement for each -wavenum-. If that is so egen numProp4 = total((wavenum == 4) * numProp) , by(id) and egen numInsArrng6 = total((wavenum == 6) * numInsArrng) , by(id) spread values in particular wave numbers to all observations with the same identifier. For example, wavenum == 4 is 1 if wavenum is 4 and 0 otherwise, so the ensuing total is just the value of numProp for wavenum == 4. The required indicator variable follows directly. Note that even Erick's -if- condition had been correct (it isn't), his expression for indicator (dummy in his terminology) would have yielded 1 and missing, not 1 and 0. Martin Weiss More Income in 1982 than in 1980? Let`s see... ********* clear* inp id year sex inc 1 80 0 5000 1 81 0 5500 1 82 0 6000 1 83 0 7000 2 80 1 2000 2 81 1 2200 2 82 1 3300 2 83 1 3500 3 80 0 3000 3 81 0 2000 3 82 0 1000 3 83 0 1000 4 80 0 3000 4 81 0 4000 4 82 0 1000 4 83 0 10000 end *mark years to compare tempvar compare g byte `compare'=year==80 | year==82 *sort them to the end, within id and respecting years, and generate indicators bys id (`compare' year) : g byte hi82=inc[_N]>inc[_N-1] *resort sort id year drop `compare' *let`s see l, noo sepby(id) Erick Guerrero, M.A. (Ph.D. Candidate) > I am trying to create a dummy > variable that is equal to 1 when organizations have more > properties in wave 6 compared to wave 4. My data is in long > form. > > Logically, it would be something like this, but this does not > work, I am missing some steps. > > gen HiPropertyw6= 1 if (numProp==wavenum==4 < > numInsArrng==wavenum==6). * * 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**:**st: RE: RE: AW: RE: Re: Generate Variable***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**st: AW: RE: AW: RE: Re: Generate Variable***From:*"Martin Weiss" <martin.weiss1@gmx.de>

**References**:**st: Generate Variable***From:*<erickg@uchicago.edu>

**st: Re: Generate Variable***From:*"Martin Weiss" <martin.weiss1@gmx.de>

**st: RE: Re: Generate Variable***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**st: AW: RE: Re: Generate Variable***From:*"Martin Weiss" <martin.weiss1@gmx.de>

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