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From |
Johannes Geyer <JGeyer@diw.de> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: is this a missing value issue? (-if- command used) |

Date |
Mon, 21 Jul 2008 15:22:30 +0200 |

Hey Andrea, I guess this is a FAQ: http://www.stata.com/support/faqs/lang/ifqualifier.html "if" works like "while" in your example, i.e. in case you have -`var'==.- and "missing" is a very large number the if-statement does not evaluate to "true" and does not execute -drop `var'-. It starts evaluating your data with the first observation. If the statement is "false", Stata proceeds executing code after the if-statement. Hope this helps, Johannes wner-statalist@hsphsun2.harvard.edu schrieb am 21/07/2008 15:05:02: > Hi! > > I have the following code in my do-file: > > qui lookfor zt > qui foreach var of varlist `r(varlist)' { > if `var'<=.1 { > drop `var' > } > } > > All my zt* variables are percentages of missing values of the original > variables, e.g. zt_age_2000==0.04 means that 0.04 percent of the > variable age in year 2000 are missing. The way I generated the zt- > variables, they contain Stata missing values for all years except the > corresponding year, e.g. in the above case the zt_age_2000 variable > contains missing values for all years smaller and greater than 2000 > while for the year 2000 it shows the percentage missing. > > Now with the above query I want to get rid of zt-variable if their > missing percentage is below the threshold of 0.1. Strangely, when I > use the above commands, it does not perform what I want. However, when > I first recode each zt-variable and set the missing values to zero, > then the if-query works fine. > > So, what am I doing wrong when using the if-command? > > Many thanks for your considerations, > > Andrea > * > * 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: is this a missing value issue? (-if- command used)***From:*Andrea Bennett <mac.stata@gmail.com>

**Re: st: is this a missing value issue? (-if- command used)***From:*Andrea Bennett <mac.stata@gmail.com>

**References**:**st: is this a missing value issue? (-if- command used)***From:*Andrea Bennett <mac.stata@gmail.com>

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