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From |
Amadou DIALLO <stata.diallo@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Spss's aggregate vs stata's collapse. |

Date |
Mon, 18 Apr 2011 17:02:16 +0300 |

I am still playing around with the weights but no results so far. Yes, I need to match exactly spss' results. Can someone show where to find spss' procedures manual?Best regards. Bachir. 2011/4/13, Kaulisch, Marc <kaulisch@forschungsinfo.de>: > Uli, > > SPSS looks inconsistent here. A look in the tutorial gives a clear insight > in the mess: > "SPSS automatically rounds weighted > frequencies to the nearest integer. This rounding is done by default on the > total weighted frequency, > not on individual weights." (p. 15) > "Rounding off these decimals is not an indifferent matter. Both 0.80 and > 1.45 will be rounded to 1, > which kills the very purpose of weighting. Suppose the weight of some cases > is 0.30. If one case > with weight 0.30 appears in a cell, the weighted (and rounded) total will be > zero cases in that cell. > If a second cell includes two cases from the same stratum, their weighted > total will be 0.60, > rounded to one case." (p.16) > > And in some procedures like CROSSTAB (Stata tab) you can turn off rounding > the weights ;-) > > Really strange this... > > Marc > > -----Ursprüngliche Nachricht----- > Von: owner-statalist@hsphsun2.harvard.edu > [mailto:owner-statalist@hsphsun2.harvard.edu] Im Auftrag von Ulrich Kohler > Gesendet: Mittwoch, 13. April 2011 15:20 > An: statalist@hsphsun2.harvard.edu > Betreff: Re: st: Spss's aggregate vs stata's collapse. > > Am Mittwoch, den 13.04.2011, 12:13 +0100 schrieb Brendan Halpin: >> On Wed, Apr 13 2011, Amadou DIALLO wrote: >> >> > Brendan, Uli, >> > Thanks for answers. Yes, it has to do with weights. Removing it >> > yields same results. Apparently SPSS rounds non-integer weight to >> > the nearest integer (the total weighted frequency, not individual >> > weights (sic!): >> > www.spsstools.net/Tutorials/WEIGHTING.pdf >> >> SPSS is doing the wrong thing here, then. >> >> > I've tried Brendan's solution but this is not working. So far, I >> > can't duplicate results and am stuck. Will continue checking. >> >> If you really need to duplicate the results, you need to replicate >> SPSS's "error". It may be enough to round the weight yourself. > > I know that this is not a SPSS list, however I'm still puzzled about what > "rounding to the nearest integer" here really means. If a sampling weight > has been rescaled such that the sum of weights is equal to the number of > observations, there will be quite a number of weights below 0.5. Are they > "rounded" to 0 then, meaning to drop them from the analysis? Or is zero not > an integer value? Or do we use, the geometric mean or harmonic mean between > two subsequent numbers as the threshold for rounding, or what. > > SPSS = Some petty Statistical Software? > > Uli > > > > * > * 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/ > -- Amadou B. DIALLO, PhD. Economist (Anti-Poverty Programs - DR Congo), AFTP3, The World Bank, Washington DC. Director, Center for Research and Training on Adult Health and Education. Mayotte (FRANCE). www.aprosasoma.org * * 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/

**References**:**AW: st: Spss's aggregate vs stata's collapse.***From:*"Kaulisch, Marc" <kaulisch@forschungsinfo.de>

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