`To get it right: Should I use the expansion factors of the subjects as
``pweights or the survey design variables? The selected sample (subgroup)
``is part of a survey with four samples. The other samples deal with
``topics, which are not interesting for me, so I have chosen only the
``subjects of that sample.
`
Jette
-----Ursprüngliche Mitteilung-----
Von: Steve Samuels <[email protected]>
An: statalist <[email protected]>
Verschickt: Di, 27 Mrz 2012 10:04 pm
Betreff: Re: AW: AW: st: error message "too many weights"

`Ah, SPSS! Base SPSS has no survey capabilities but does estimate
``"weighted" (i.e. frequency-weighted) statistics. I'll bet that many
``unsuspecting investigators have reported wrong standard errors and
``p-values for those statistics. You should use pweights. You need a
``very good reason to ignore the other survey design variables-PSU and
``stratum. Having "one sample" (a subgroup?) is not good reason unless
``its members reside in a very small number of PSUs. Then you would need
``to include the PSU & strata as covariates. [email protected]
``Mar 27, 2012, at 1:43 PM, Jette Kellerhoff wrote:Thanks for your
``advice. It is true, that the data is part of a survey, but Ihave chosen
``only the subjects of one sample. The variable gew represents thereal
``abundance pattern of these subjects - the values of gew are
``theexpansion factors. The expansion factors of the subjects are
``multiplied bythe probability to stay in the panel. Is it correct to use
``fweight in thatcase, or pweight? I am not used to Stata, normally I use
``SPSS.Jette -----Ursprüngliche Nachricht-----Von:
``[email protected][mailto:[email protected]
``ard.edu] Im Auftrag von Steve SamuelsGesendet: Dienstag, 27. März 2012
``11:14An: [email protected]: Re: AW: AW: st: error
``message "too many weights"Jette Kellerhoff-Your use of the words
``"panel" and "wave". suggests that you have surveydata. If so, the
``weight should be designated a probability weight (pweight).At a minimum
``then, you need [pweight = gew] in the -stset- statement. Thiswill give
``you properly weighted estimates of descriptive statistics like
``thesurvival curve. If the survey had a multi-stage design and you
``intend to run regressioncommands like -stcox-, you will need to
``-svyset- the data. If you don't,standard errors and p-values will be
``wrong. The -svyset- statement has
``theform:*********************************************svyset psu_var [pw
``= gew],
``strata(stratum_var)*********************************************After
``that, use the -svy:- prefix for -stcox- and -streg-. If you are
``planning multiple failure time analyses and weights areconstant within
``id, then you will be omit the cluster(id) option in -stset-.That won't
``matter, because standard errors will be based on the surveydesign. If
``weights are not constant within ID, -stset- will complain. So
``checkfirst. You have multiple spell data, apparently, and I'm not sure
``of yourdata structure. But a generic solution is to add an enter()
``option to the-stset- statement and omit the id() option. The code would
``be somethinglike:*************CODE BEGINS*************svyset psu_var
``[pw = gew], strata(stratum_var)stset tfp , fail(event indicator)
``enter(start time for spell) exit(time.)svy: stcox // etc.
``**************************************[email protected] also:
``http://www.stata.com/statalist/archive/2008-10/msg01494.html. On Mar
``26, 2012, at 5:03 AM, Nick Cox wrote:I could tell you how to force
``non-integers to integers but I fear thatwould be telling how to force
``your problem into an incorrect ordubious application of -st-.I am in no
``sense an expert on survival analysis, so I won't commentfurther. This
``may or may not be enough information for someonecompetent in that field
``to get a sense of what your real problem isand give better
``advice.NickOn Mon, Mar 26, 2012 at 9:44 AM, Jette Kellerhoff
``<[email protected]> wrote:> For each subject exists a weight (variable
``gew), which identifies the real> abundance pattern in time. The
``computed values of the variable gew are the> result of the real
``abundance pattern multiplied by the probability to stay> in the panel.
``So in many cases the results are not integers. How to create>
``integers?Nick Cox> I could tell you about Stata. But you really need to
``explain what the> variable -gew- is, why some values are not integers,
``and why you want> to treat them as frequency weights.On Sun, Mar 25,
``2012 at 6:50 PM, Jette Kellerhoff <[email protected]> wrote:>> There are
``some non-integer values. How to create integers?Nick Cox>> The
``implication is that your variable -gew- contains non-integer>> values.
``Is that true?>> >> . list gew if gew != floor(gew)>> >> fweights
``indicate frequencies, which must be integers.On Sun, Mar 25, 2012 at
``6:09 PM, Jette Kellerhoff <[email protected]>>>> I removed the first
``bracket, but the error message is still the same:may>>> not use
``noninteger frequency weights>>> stset tfp [fweight = gew], id(hhnrakt)
``f(des=2 4 6 8 10 12) exit(time .)Steve Samuels>>> You did not follow my
``advice to look at the examples. You only removed> the>>> last bracket;
``the beginning "[" of the second pair remains.On Mar 25, 2012, at 12:40
``PM, Jette Kellerhoff wrote:>>> Thanks for your advice. If I remove the
``brackets, I get the following>> error>>> message may not use noninteger
``frequency weights. I don't understand it,>>> because fweights are
``allowed in the stset-command.>>> The do-file:>>> stset tfp
``[fweight=gew] [ ,id(hhnrakt) f(des=2 4 6 8 10 12) exit(time.)Steve
``Samuels>>> I should add that in the -help- for -stset-, the brackets
``indicate where>>> options, if any, should go. Before running an
``unfamiliar command, always>>> look at the examples at the bottom of the
``help screen or in the manual.>>> Remove the second pair of brackets in
``your -stset- statement. They are> not>>> legal Stata syntax.On Mar 22,
``2012, at 3:18 PM, Jette Kellerhoff wrote:>>> Sorry for the
``impatientness, but I have to solve the problem very soon.>>> The
``case:>>> - 4841 subjects with multiple record per subject (max 4
``records)>>> - for each subject exists a weight, which identifies the
``real abundance>>> pattern in time>>> >>> I used the following
``do-file:>>> gen des =tfin~=ti>>> >>> gen tf = tfin-tstart+1>>> >>> gen
``org=1+2*(spell-1)>>> replace des=org>>> replace des=org+1 if tfin<ti>>>
``gen tfc=tstart if spell==1>>> replace tfc=tfc[_n-1] if spell~=1 &
``hhnrakt==hhnrakt[_n-1]>>> gen tsp = tstart-tfc>>> gen tfp =
``tfin-tfc+1>>> stset tfp [fweight=gew] [ ,id(hhnrakt) f(des=2 4 6 8 10
``12) exit(time.)]Richard Herron>>> Jette, can you provide a reproducible
``example? That may help diagnose>>> your problem. Can you reproduce the
``error with -sysuse- data or>>> provide your console output, please?On
``Thu, Mar 22, 2012 at 14:34, Jette Kellerhoff <[email protected]>
``wrote:>>>> how to deal with weights according to survival data
``analysis? If I use>>>> fweights according to stset command, I get the
``error message "too many>>>> weights". Does anyone have any
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