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From |
Nick Cox <njcoxstata@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: How can I replace missing values with the variable's first nonmissing value? |

Date |
Sat, 11 Aug 2012 19:35:07 +0100 |

A similar way to do it: gen obs = _n su obs if !missing(x), meanonly replace x = x[r(min)] if _n < r(min) For more examples hinging on a variable constructed to contain _n, see SJ-6-3 dm0025 . . . . . . . . . . . . . . Stata tip 36: Which observations? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox Q3/06 SJ 6(3):430--432 (no commands) tip for identifying which observations satisfy some specified condition SJ-6-4 dm0025 . . . . . . . . . . Stata tip 36: Which observations? Erratum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox Q4/06 SJ 6(4):596 (no commands) correction of example code for Stata tip 36 On Sat, Aug 11, 2012 at 5:08 PM, Airey, David C <david.airey@vanderbilt.edu> wrote: > Here is a try: > > clear > set obs 100 > gen x = runiform() > gen y = runiform() > replace x = . if y > 0.8 // 20% missing > drop y > gen notmissing = _n if !missing(x) > egen r1 = min(notmissing) > gen r2 = x[r1] > gen x2 = x > replace x2 = r2 if missing(x) > drop notmissing r1 r2 > browse Yuelian Sharon >> I want to replace a variable's missing value with its first nonmissing >> value, how can I realize this? I read the FAQ at >> >> http://www.stata.com/support/faqs/data-management/replacing-missing-values/ >> , >> but there is no example for my case. >> >> My data structure is like : >> >> _n myvar >> 1 . >> 2 . >> 3 . >> 4 1 >> 5 2 >> 6 6 >> 7 . >> >> After replacement, I want to get data as: >> >> _n myvar >> 1 1 >> 2 1 >> 3 1 >> 4 1 >> 5 2 >> 6 6 >> 7 1 * * 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/

**References**:**re: st: How can I replace missing values with the variable's first nonmissing value?***From:*"Airey, David C" <david.airey@vanderbilt.edu>

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