Re: AW: AW: st: error message "too many weights"

[jettek82@aol.com]

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 <sjsamuels@gmail.com>
An: statalist <statalist@hsphsun2.harvard.edu>
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.  Stevesjsamuels@gmail.comOn 
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: 
owner-statalist@hsphsun2.harvard.edu[mailto:owner-statalist@hsphsun2.harv
ard.edu] Im Auftrag von Steve SamuelsGesendet: Dienstag, 27. März 2012 
11:14An: statalist@hsphsun2.harvard.eduBetreff: 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.   
**************************************Stevesjsamuels@gmail.comSee 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 
<jettek82@aol.com> 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 <jettek82@aol.com> 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 <jettek82@aol.com>>>> 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 <jettek82@aol.com> 
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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