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

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Double loop over unbalanced panel |

Date |
Sat, 3 Nov 2012 09:12:48 +0000 |

I agree with Sylvain. Apart from a twist which does not make the Stata code much more difficult, this looks like a standard problem discussed in an FAQ FAQ . . . . . . . . . . . . . . . . . . . . . . . Replacing missing values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox 2/03 How can I replace missing values with previous or following nonmissing values? http://www.stata.com/support/faqs/data-management/replacing-missing-values/ On Sat, Nov 3, 2012 at 5:53 AM, WEBER Sylvain <sylvain.weber@unine.ch> wrote: > I think you don't need any loop. - by - can be used instead. > Try > bysort id (t): replace chc=(chc[_n-1]*ph+cont)/p if mi(chc) > > Note that the - if mi(chc) - condition is very important. Otherwise, you would replace all values of chc; not only missing values. Le 2 nov. 2012 à 14:00, "Fernando Luco" <flucoestatalist@gmail.com> a écrit : >> The data and the formula look as follows >> >> input id t str1 ch p str1 chh ph cont con_c chc >> 1 1 "a" 2 "" . 1 0.5 1 1 >> 1 2 "b" 3 "a" 4 3 1 . >> 1 2 "b" 3 "a" 4 3 1 . >> 1 3 "a" 1 "b" 2 2 2 . >> 1 4 "c" 4 "a" 3 3 .75 . >> 1 5 "d" 2 "c" 5 1 .5 . >> 2 3 "d" 2 "" . 1 1 2 >> 2 4 "a" 3 "d" 3 3 1 . >> 2 5 "b" 1 "a" 2 2 2 . >> 2 6 "a" 2 "b" 2 1 .5 . >> end >> >> foreach k of numlist 1/2{ >> foreach w of numlist 2/T_k{ >> replace chc=(chc[`w'-1]*ph+cont)/p if _n==`w' & id==`k' >> } >> } On Fri, Nov 2, 2012 at 3:39 PM, Nick Cox <njcoxstata@gmail.com> wrote: >>> I think the best advice depends on what -formula()- is, which you >>> don't tell us. >>> >>> That said >>> >>> foreach of numlist ... >>> >>> in both your examples can be recast more simply as -forval- loops. On Fri, Nov 2, 2012 at 8:12 PM, Fernando Luco <flucoestatalist@gmail.com> wrote: >>>> I have an unbalanced panel and I need to do a loop over individuals and >>>> observations. My data looks as follows (I have other variables that are not >>>> represented in this example) >>>> >>>> id t chc >>>> 1 1 .5 >>>> 1 2 . >>>> 1 3 . >>>> 1 4 . >>>> 1 5 . >>>> 2 3 1 >>>> 2 4 . >>>> 2 5 . >>>> 2 6 . >>>> >>>> What I want to do is, for each individual (id) to complete the values in >>>> chc according to a formula that depends on other variables. However, the >>>> number of times that each individual appears differs across individuals. I >>>> would like to do something such as >>>> >>>> foreach k of numlist 1/2 { /*the 2 has to be changed to the total number of >>>> individuals*/ >>>> foreach w of numlist 2/T_k { /* where T_k corresponds to the number of >>>> times individual 2 appears*/ >>>> replace chc=formula(`w') >>>> } >>>> } >>>> >>>> I don't know how to define T_k in the correct way such that it varies >>>> across individuals (so 5 for individual 1 and 4 for individual 2). * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: Double loop over unbalanced panel***From:*Fernando Luco <flucoestatalist@gmail.com>

**References**:**st: Double loop over unbalanced panel***From:*Fernando Luco <flucoestatalist@gmail.com>

**Re: st: Double loop over unbalanced panel***From:*Nick Cox <njcoxstata@gmail.com>

**Re: st: Double loop over unbalanced panel***From:*Fernando Luco <flucoestatalist@gmail.com>

**Re: st: Double loop over unbalanced panel***From:*WEBER Sylvain <sylvain.weber@unine.ch>

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