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Re: st: SVY medians and Elixhauser
From
Mike Butterfield <[email protected]>
To
[email protected]
Subject
Re: st: SVY medians and Elixhauser
Date
Sun, 14 Apr 2013 22:11:14 -0700
Hi Steve (thanks for the reference) and Stas- I had some trouble with
epctile and wanted to get your opinion on whether this is ‘legal’
(legitimate) to do.
1. I tried to get median ages for my patients with portal vein
thrombosis (pvt) for both those with& without cirrhosis, but I had
some strata with single observations.
2. I identified the strata and excluded them (~6 observations), and
got it to work.
3. Is ok to do? Output for non cirrhotics is below.
a. This didn’t work:
. epctile AGE, p(50) over(cirr) svy speclab subpop(pvt if AGE>=18 & AGE<=90)
(running mean on estimation sample)
Survey: Mean estimation
Number of strata = 53 Number of obs = 3665
Number of PSUs = 482 Population size = 18356
Subpop. no. obs = 3665
Subpop. size = 18356
Design df = 429
0: cirr = 0
1: cirr = 1
--------------------------------------------------------------
| Linearized
Over | Mean Std. Err. [95% Conf. Interval]
-------------+------------------------------------------------
__000006 |
0 | -.0236348 . . .
1 | -.0477322 . . .
--------------------------------------------------------------
Note: missing standard errors because of stratum with single
sampling unit.
estimates post: matrix has missing values
r(504);
b. this did:
svydes AGE if AGE>=18 & AGE<90 & pvt==1 & cirr==0
Survey: Describing stage 1 sampling units
pweight: DISCWT
VCE: linearized
Single unit: missing
Strata 1: NIS_STRATUM
SU 1: HOSPID
FPC 1: <zero>
#Obs with #Obs with #Obs per included Unit
#Units #Units complete missing ----------------------------
Stratum included omitted data data min mean max
-------- -------- -------- -------- -------- -------- -------- --------
2111 1* 0 1 0 1 1.0 1
2412 1* 0 1 0 1 1.0 1
3111 1* 0 1 0 1 1.0 1
3112 1* 0 1 0 1 1.0 1
3121 1* 0 1 0 1 1.0 1
4112 1* 0 1 0 1 1.0 1
4122 1* 0 4 0 4 4.0 4
-------- -------- -------- -------- -------- -------- -------- --------
51 399 0 1495 0 1 3.7 69
------------------
. epctile AGE, p(50) svy speclab subpop(pvt if AGE>=18 & AGE<=90 &
cirr==0 & NIS_STRATUM ~=2111 & NIS_STRATUM ~=2412 & NIS_STRATUM ~=3111
& NIS_STRATUM ~=3112 & NIS_STRATUM ~=3121 & NIS_STRATUM ~=4112)
Number of strata = 44 Number of obs = 1492
Number of PSUs = 394 Population size = 7486.8
Subpop. no. obs = 1492
Subpop. size = 7486.8
Design df = 350
...
Percentile estimation
------------------------------------------------------------------------------
| Linearized
AGE | Coef. Std. Err. z P>|z| [95% Conf. Interval]
-------------+----------------------------------------------------------------
p50 | 56 .75 74.67 0.000 54.53003 57.46997
Mike
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