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From |
Steve Samuels <sjsamuels@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: Re: st: RE: AW: ratio function |

Date |
Tue, 27 Apr 2010 07:37:47 -0400 |

Sorry, I don't have version 10, but use Martin's trick ************* suest, coefl ************* to see what Stata does call these in Version 10. In Version 11 both syntaxes work. Why your errors? I don't have Verstion 10, but my guess is that it's because -mean- and -svy: mean- are not regression commands. They will take multiple variables, so there is no "constant". **************** sysuse auto, clear svy: mean mpg weight di _b[mpg] _b[weight] -suest- only works with commands for which -predict- is a valid post-estimation command. (See the -help-) That's not true of -mean- or -svy: mean-That's probably the source of the error message, at least indirectly. In addition, -suest- is not necessary after -mean, over()-, because all the results are already available to -nlcom-. Steve 2010/4/27 Roman Kasal <kasal@trexima.cz>: > "nlcom _b[y2008:_cons]/_b[y2009:_cons]" really don't work for me (STATA 10.1) but "nlcom [y2008]_cons/[y2009]_cons" does > > btw, don't you know why this code ends with an error? > > ******************** > est drop _all > svyset ICO [pw=vahaHMM], strata(stk2) fpc(fpc1) singleunit(centered) > svy: mean hrMzdaMes if rok==2009 > est sto r2009 > svy: mean hrMzdaMes if rok==2008 > est sto r2008 > est dir > > ------------------------------------------------------- > name | command depvar npar title > -------------+----------------------------------------- > r2009 | mean no depvar 1 > r2008 | mean no depvar 1 > ------------------------------------------------------- > suest r2009 r2008 > impossible to retrieve e(b) and e(V) in r2009 > **************** > > And does suest handle with "svy:mean x, over(y)"? > > > > -----Original Message----- > From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Steve Samuels > Sent: Monday, April 26, 2010 2:17 PM > To: statalist@hsphsun2.harvard.edu > Subject: Re: Re: st: RE: AW: ratio function > > You're very welcome. Either syntax works. See section 13.5 of the User's Guide. > > Steve > > 2010/4/26 Roman Kasal <kasal@trexima.cz>: >> thank you, it helps a lot! >> >> just small correction: >> >> the last command should by "nlcom [y2008]_cons/[y2009]_cons" I assume >> >> roman >> >> -----Original Message----- >> From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Steve Samuels >> Sent: Monday, April 26, 2010 1:23 AM >> To: statalist@hsphsun2.harvard.edu >> Subject: Re: Re: st: RE: AW: ratio function >> >> My previous example was flawed, Because males and females could be >> present in the same PSU (famid), the degrees of freedom for -suest- >> did not equal the sum of the d.f. for the separate regressions. Here >> is another example with proper strata. Note that the degrees now add >> properly. >> Steve >> >> ************************* >> webuse income, clear >> gen year = 2008 + (famid>68) >> tab year >> svyset famid, strata(year) >> svy: reg inc if year==2008 >> estimates store y2008 >> svy: reg inc if year==2009 >> estimates store y2009 >> suest y2008 y2009 >> matrix list e(V) //results from different years are independent >> nlcom _b[y2008:_cons]/_b[y2009:_cons] >> *********************************************** >> On Fri, Apr 23, 2010 at 10:40 AM, Steve Samuels <sjsamuels@gmail.com> wrote: >>> Just use -suest-. Use the fact that -reg- without an argument is >>> equivalent to estimating the mean. >>> >>> ******************** >>> webuse income, clear >>> svyset famid >>> svy: reg inc if male >>> estimates store Male >>> svy: reg inc if !male >>> estimates store Female >>> suest Male Female >>> nlcom _b[Male:_cons]/_b[Female:_cons] >>> ************************* >>> Steve >>> >>> 2010/4/23 Roman Kasal <kasal@trexima.cz>: >>>> yes, the year is another survey (different time; the years cannot be pooled because of degrees of freedom) and is included in strata. >>>> >>>> so there is no solution for this case? just manually? >>>> >>>> -----Original Message----- >>>> From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Steve Samuels >>>> Sent: Friday, April 23, 2010 1:32 PM >>>> To: statalist@hsphsun2.harvard.edu >>>> Subject: Re: Re: st: RE: AW: ratio function >>>> >>>>> "svy: mean wage, over(year)" is not equal "svy: mean wage if year==2009" >>>> >>>> The "if statement" is incorrect, unless year was a stratification >>>> variable that you identified to Stata. >>>> >>>> -nlcom- after -svy: mean-, over(year), is the proper approach. >>>> >>>> >>>> 2010/4/23 Roman Kasal <kasal@trexima.cz>: >>>>> ok, for this purpose I agree, that is ok...but what about if I want to calculate SE of Mean in years 2009 and 2008 and then ratio with SE of the means? >>>>> >>>>> the problem is that CI of >>>>> "svy: mean wage, over(year)" is not equal "svy: mean wage if year==2009" >>>>> for the year 2009 because of different degrees of freedom (SE's are equal), the first command gives wrong CI. >>>>> >>>>> is any elegant solution to handle this in Stata with "nlcom" or do I have to calculate it manually? >>>>> >>>>> thank you >>>>> >>>>> -----Original Message----- >>>>> From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Steve Samuels >>>>> Sent: Thursday, April 22, 2010 3:08 PM >>>>> To: statalist@hsphsun2.harvard.edu >>>>> Subject: Re: Re: st: RE: AW: ratio function >>>>> >>>>> The degrees of freedom are correct. See any sampling text. >>>>> >>>>> Briefly: To identify a subpopulation, each observation in the sample >>>>> receives a 0-1 indicator variable d. If X is the numerator variable >>>>> and Y is the denominator variable, the numerator for the ratio of is >>>>> the sum *over the entire sample* of Z_x = d *X and the denominator is >>>>> the sum of Z_y = d * Y. The standard errors are based on variability >>>>> in the Z's, including the zero values. >>>>> By the way, the standard errors formulas are valid only if the >>>>> expected number of observations in a subpopulation is at least 20. >>>>> >>>>> Steve >>>>> >>>>> 2010/4/22 Roman Kasal <kasal@trexima.cz>: >>>>>> thank you for the code, but I have found a problem: >>>>>> >>>>>> if I calculate over(foreign) the bound are enumerated with "e(N_psu)-e(N_strata)" degrees of freedom, but not for each foreign (degrees of freedom are for whole dataset) and this is wrong I assume. >>>>>> >>>>>> thank you >>>>>> >>>>>> -----Original Message----- >>>>>> From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Steve Samuels >>>>>> Sent: Friday, April 02, 2010 2:58 PM >>>>>> To: statalist@hsphsun2.harvard.edu >>>>>> Subject: Re: Re: st: RE: AW: ratio function >>>>>> >>>>>> Roman >>>>>> Perhaps we misunderstand what you are asking for. I We have been >>>>>> assuming that you want the ratio of the means of two variables >>>>>> ("columns"?) measured possibly on the same person. Perhaps you want >>>>>> the ratio of the means of one variable for two subpopulations. Both >>>>>> analyses will ignore missing values. >>>>>> >>>>>> If this is not what you desire, then please demonstrate by hand what >>>>>> you do want on a small, non-survey data set.. Also I'd like to know >>>>>> which R function does what are asking for >>>>>> >>>>>> The following do file computes the ratio of means with CI and then >>>>>> does the same for the log ratio and transforms to the original scale. >>>>>> >>>>>> -Steve >>>>>> >>>>>> >>>>>> **************************CODE BEGINS************************** >>>>>> capture program drop _all >>>>>> program antilog >>>>>> local lparm el(r(b),1,1) >>>>>> local se sqrt(el(r(V),1,1)) >>>>>> local bound invttail(e(df_r),.025)*`se' >>>>>> local parm exp(`lparm') >>>>>> local ll exp(`lparm' - `bound') >>>>>> local ul exp( `lparm' + `bound') >>>>>> di "parm =" `parm' " ll = " `ll' " ul = " `ul' >>>>>> end >>>>>> >>>>>> sysuse auto, clear >>>>>> svyset _n >>>>>> svy: mean mpg, over(foreign) >>>>>> nlcom (myratio1: _b[Domestic]/_b[Foreign]) //ratio >>>>>> nlcom (myratio2: log(_b[Domestic]/_b[Foreign])) // log ratio >>>>>> // Confidence interval of last -nlcom- on antilog scale >>>>>> antilog >>>>>> ***************************CODE ENDS*************************** >>>>>> >>>>>> >>>>>> >>>>>> . >>>>>> >>>>>> On Fri, Apr 2, 2010 at 2:37 AM, Roman Kasal <kasal@trexima.cz> wrote: >>>>>>> I don't agree...so how to do it when you want to find out ratio between >>>>>>> years, male X female, ...? So there is no solution? Just to keep N,mean, >>>>>>> SE, degrees of freedom, N_strata, N_psu, .... and calculate it manually? >>>>>>> I think it is not appropriate solution, at least to have it as an >>>>>>> option. I think there is missing a lot with complex survey in Stata and >>>>>>> complex survey is needed for almost every survey research, even freeware >>>>>>> R-project is better equipped :( >>>>>>> >>>>>>> so have a hope Stata will get it soon....immediately we are buying it >>>>>>> again :) >>>>>>> >>>>>>>> >>>>>>>> >>>>>>> And it should. Data (x,y) (1,2) (2,4) (3,6) (100,.) will give an >>>>>>> entirely different view of the data if the unpaired observation is >>>>>>> included in a mean or ratio calculation. Or consider data with x >>>>>>> missing in half the pairs and y missing in the other half; the ratio >>>>>>> of means would be meaningless. >>>>>>> >>>>>>> The formulas for standard errors for ratios assume that the data are >>>>>>> paired. Formally, they are based on the residual MSE of a regression >>>>>>> of y on x through the origin. You cannot do that regression with >>>>>>> unpaired data. >>>>>>> >>>>>>> If your concern is missing data, the solution is to impute the missing >>>>>>> values before analysis. >>>>>>> >>>>>>> Steve >>>>>>> >>>>>>> >>>>>>> * >>>>>>> * 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/ >>>>>>> >>>>>> >>>>>> >>>>>> >>>>>> -- >>>>>> Steven Samuels >>>>>> sjsamuels@gmail.com >>>>>> 18 Cantine's Island >>>>>> Saugerties NY 12477 >>>>>> USA >>>>>> Voice: 845-246-0774 >>>>>> Fax: 206-202-4783 >>>>>> >>>>>> * >>>>>> * 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/ >>>>>> >>>>> >>>>> >>>>> >>>>> -- >>>>> Steven Samuels >>>>> sjsamuels@gmail.com >>>>> 18 Cantine's Island >>>>> Saugerties NY 12477 >>>>> USA >>>>> Voice: 845-246-0774 >>>>> Fax: 206-202-4783 >>>>> >>>>> * >>>>> * 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/ >>>>> >>>> >>>> >>>> >>>> -- >>>> Steven Samuels >>>> sjsamuels@gmail.com >>>> 18 Cantine's Island >>>> Saugerties NY 12477 >>>> USA >>>> Voice: 845-246-0774 >>>> Fax: 206-202-4783 >>>> >>>> * >>>> * 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/ >>>> >>> >>> >>> >>> -- >>> Steven Samuels >>> sjsamuels@gmail.com >>> 18 Cantine's Island >>> Saugerties NY 12477 >>> USA >>> Voice: 845-246-0774 >>> Fax: 206-202-4783 >>> >> >> >> >> -- >> Steven Samuels >> sjsamuels@gmail.com >> 18 Cantine's Island >> Saugerties NY 12477 >> USA >> Voice: 845-246-0774 >> Fax: 206-202-4783 >> >> * >> * 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/ >> > > > > -- > Steven Samuels > sjsamuels@gmail.com > 18 Cantine's Island > Saugerties NY 12477 > USA > Voice: 845-246-0774 > Fax: 206-202-4783 > > * > * 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/ > -- Steven Samuels sjsamuels@gmail.com 18 Cantine's Island Saugerties NY 12477 USA Voice: 845-246-0774 Fax: 206-202-4783 * * 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: Re: st: RE: AW: ratio function***From:*Steve Samuels <sjsamuels@gmail.com>

**RE: Re: st: RE: AW: ratio function***From:*"Janssen, Nathalie (Stud. FPN / Alumni)" <njjf.janssen@student.maastrichtuniversity.nl>

**AW: Re: st: RE: AW: ratio function***From:*"Martin Weiss" <martin.weiss1@gmx.de>

**References**:**Re: Re: st: RE: AW: ratio function***From:*"Roman Kasal" <kasal@trexima.cz>

**Re: Re: st: RE: AW: ratio function***From:*Steve Samuels <sjsamuels@gmail.com>

**RE: Re: st: RE: AW: ratio function***From:*"Roman Kasal" <kasal@trexima.cz>

**Re: Re: st: RE: AW: ratio function***From:*Steve Samuels <sjsamuels@gmail.com>

**RE: Re: st: RE: AW: ratio function***From:*"Roman Kasal" <kasal@trexima.cz>

**Re: Re: st: RE: AW: ratio function***From:*Steve Samuels <sjsamuels@gmail.com>

**Re: Re: st: RE: AW: ratio function***From:*Steve Samuels <sjsamuels@gmail.com>

**RE: Re: st: RE: AW: ratio function***From:*"Roman Kasal" <kasal@trexima.cz>

**Re: Re: st: RE: AW: ratio function***From:*Steve Samuels <sjsamuels@gmail.com>

**RE: Re: st: RE: AW: ratio function***From:*"Roman Kasal" <kasal@trexima.cz>

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