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From |
JLGreig <jlgreig@yahoo.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: RE: RE: geometric mean saved results |

Date |
Wed, 18 Sep 2002 14:58:01 -0700 (PDT) |

Well, I've removed the need for the "if `1'~=9999" and the below does perform ranksums, however I'm still concerned since each p-value is exactly the same for all the ten variables (var1-var10) in the output. Also, when I substitute regresss for ranksum, only coefficients appear in the output tables--with "." appearing in the regression output columns for Std. Err., t, P>|t|, etc., ...so now I'm REALLY scared.(!) But thanks anyways. If the other STATA gods have suggestions, I'll still take 'em. --- "Steichen, Thomas" <STEICHT@RJRT.com> wrote: > JL Greig writes: > > > I apologize--let me provide a few more details. > The > > previous was actually part of a larger little > program > > which essentially used a portion of a large > database > > (gender==1), displayed a description of the > ranksum to > > be performed, quietly tabulated the arithmetic, > > geometric, and harmonic means of a continuous > variable > > then attempted to ranksum test for differences in > the > > geometric means of that continuous variable across > > categories of categorical variables noted as `1' > (var1 > > var2), as in the below, full program. There is > only > > one observation of the continuous variable per id. > > > > > capture program drop taball > > program define taball > > while "`1'" ~="" { > > use database1, clear > > keep if gender==1 > > display "ranksum GEOMETRIC MEAN fp3 by `1' " > > sort `1' > > quietly means fp3 > > local `gmeanfp3' = r(mean_g) > > ranksum `gmeanfp3' if `1'~=9999, by(`1') > > mac shift > > } > > end > > taball var1 var2 > > > > > > I can report the geometric means of my continuous > > variable across categories of var1, etc., but I > want > > to test if there are differences in these > geometric > > means of the continuous variable between those > > categories of var1, if that makes sense. > > > > I know that the local macro generates a constant, > and > > thus the above would not work, however I can't > think > > of alternatives at this point. > > > > Again, any suggestions would be appreciated. > > Consider rewriting your code as: > > ------------------------------------------------------- > capture program drop taball > program define taball > use database1, clear > keep if gender == 1 > > tempvar log_fp3 mlog_fp3 gm_fp3 > > while "`1'" ~= "" { > display "ranksum GEOMETRIC MEAN fp3 by `1'" > sort `1' > > * manually generate geometric means within > levels of `1' > qui gen `log_fp3' = log(fp3) > qui egen `mlog_fp3' = mean(`log_fp3'), by(`1') > qui gen `gm_fp3' = exp(`mlog_fp3') > > ranksum `gm_fp3' if `1' ~= 9999, by(`1') > > drop `log_fp3' `mlog_fp3' `gm_fp3' > > mac shift > } > end > > taball var1 var2 > --------------------------------------------------------- > > Having done that, you should note that using the > geometric > mean is no different from using the mean. Ranks are > > preserved by this transformation, so the statistics > in > -ranksum- will be identical. > > Also, I would be concerned of the effect of using > the > "if `1' ~= 9999" qualifier for -ranksum- while not > enforcing > it on the calculation of the geometric means. > > Overall, It seems more likely to me that you must > want the geometric > means of fp3 computed for levels of a different > categorical variable > (not `1'), as the above approach seems to accomplish > nothing useful. > > Tom > > CONFIDENTIALITY NOTE: This e-mail message, > including any attachment(s), contains information > that may be confidential, protected by the > attorney-client or other legal privileges, and/or > proprietary non-public information. If you are not > an intended recipient of this message or an > authorized assistant to an intended recipient, > please notify the sender by replying to this message > and then delete it from your system. Use, > dissemination, distribution, or reproduction of this > message and/or any of its attachments (if any) by > unintended recipients is not authorized and may be > unlawful. > > __________________________________________________ Do you Yahoo!? Yahoo! News - Today's headlines http://news.yahoo.com * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: RE: RE: geometric mean saved results***From:*"Steichen, Thomas" <STEICHT@RJRT.com>

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