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

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

Subject |
RE: st: How does Stata calculate percentiles? |

Date |
Sun, 24 Oct 2010 17:42:23 +0100 |

Phil gave a good answer. However, once you have the -centile- result in memory, local cutpoint=r(c_1) recode price (min/`cutpoint'=0) (`cutpoint'/max=1), gen(pricecat) can be replaced by one line gen pricecat = (price >= r(c_1)) if !missing(price) which yields 0, 1 and numeric missing as appropriate. On the other hand, why do you want to throw away information like this? Nick n.j.cox@durham.ac.uk Phil Clayton One way to do it would be to obtain the centile using the -centile- command, then -recode- the variable to create the indicator variable. Example: sysuse auto centile price, centile(33) local cutpoint=r(c_1) recode price (min/`cutpoint'=0) (`cutpoint'/max=1), gen(pricecat) If you wanted the indicator variable to be 1 if the variable is >= the cutpoint (as opposed to >), swap the two recoding rules (once one rule is matched, the subsequent rules are ignored). See the manual for -centile- to see how it's calculated. It's pretty standard. With regards to "su varname, d", see -help summarize- and the manual for -summarize- On 24/10/2010, at 3:27 PM, Grace Jessie wrote: > I want to generate a new variable equaling 1 if the other variable is greater than its 100/3 percentile and 0 otherwise.How to get the 100/3th percentile of a variable? > And how does Stata calculate percentiles if the number of observations is odd or even? > Additionally, what does the output "smallest and largest" mean after "su varname,d"? * * 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: How does Stata calculate percentiles?***From:*Grace Jessie <gracejessie@hotmail.com>

**References**:**st: How does Stata calculate percentiles?***From:*Grace Jessie <gracejessie@hotmail.com>

**Re: st: How does Stata calculate percentiles?***From:*Phil Clayton <philclayton@internode.on.net>

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