Notice: On March 31, it was **announced** that Statalist is moving from an email list to a **forum**. The old list will shut down on April 23, and its replacement, **statalist.org** is already up and running.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

From |
robert hartman <rohartman@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Collecting Statistics of Averages of Variables |

Date |
Sat, 29 Sep 2012 17:35:52 -0400 |

By my lights, the number of unique combinations of 2 variables from a pool of 70 variables is 2415. That's a lot but not intractable On Sat, Sep 29, 2012 at 12:39 PM, Clyde B Schechter <clyde.schechter@einstein.yu.edu> wrote: > Robert Hartman asked about calculating summary statistics from all possible combinations of some variables. The example in his initial post involved 4 variables, which should be no problem at all. But at the end of his post he says: > > "I have about a 70 variable space from which to create all these subset combinations." > > If that means that he wants to do this for all possible combinations of 70 variables, that is 2^70 (= 1.181e+21) combinations to work out. That's beyond merely time consuming: if each combination can be completely processed in 1 microsecond, we are looking at over 37,000,000 years of processing. It's examples like this that evoke the phrase "combinatorial explosion." > > Perhaps the whole approach needs to be reconsidered. > > Clyde Schechter > Dept. of Family & Social Medicine > Albert Einstein College of Medicine > Bronx, NY, USA > > * > * 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/ * * 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: Collecting Statistics of Averages of Variables***From:*robert hartman <rohartman@gmail.com>

**References**:**Re: st: Collecting Statistics of Averages of Variables***From:*Clyde B Schechter <clyde.schechter@einstein.yu.edu>

- Prev by Date:
**Re: st: RE: Looping within a subset under a certain condition** - Next by Date:
**Re: st: comparing 25th percentile survival time between two race groups** - Previous by thread:
**Re: st: Collecting Statistics of Averages of Variables** - Next by thread:
**Re: st: Collecting Statistics of Averages of Variables** - Index(es):