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Re: st: Need help for chi-square test with survey command


From   Mihir <mihir.statistics@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Need help for chi-square test with survey command
Date   Thu, 1 Oct 2009 21:19:20 +0800

Dear all:

Anybody has any idea what can be done in the case below?

Thanking you,
Mihir

On Wed, Sep 30, 2009 at 1:29 AM, Mihir <mihir.statistics@gmail.com> wrote:
>
> Dear all:
>
> I am stuck with a problem in pearson chi-square test with survey
> command. I have setup survey setting for Nationwide Inpatient Survey
> (NIS) data. I used hospital id as sampling unit, discwt as sampling
> weight and stratum variable as strata as suggested on NIS website.
> When I am trying to run chi-square test for independence between age
> category and year of data collection from 1998 to 2007, it gives
> proper result, but when I run the same command by retaining only two
> years (1998 and 2007), it does not produce p-value. I don't understand
> why it is happening? Can anybody help me - what I should do? I am also
> getting similar results with other variables that same command works
> with more year but doesn't work with two years.
>
> I have pasted my output for your ready reference.
>
> Thanking you in advance,
> Mihir
>
> svyset hospid [pweight=discwt], strata(stratum) vce(linearized)
>
>      pweight: discwt
>          VCE: linearized
>     Strata 1: stratum
>         SU 1: hospid
>        FPC 1: <zero>
>
> svy: tabulate year age2cat, count column row obs percent format(%10.0g) pearson
> (running tabulate on estimation sample)
>
> Number of strata   =        60                  Number of obs      =    157222
> Number of PSUs     =      3270                  Population size    = 759816.12
>                                                Design df          =      3210
>
> -------------------------------------------
>          |             age2cat
>     YEAR |  <65 year   >=65 yea      Total
> ----------+--------------------------------
>     1998 | 27548.394  10497.654  38046.048
>          | 72.408029  27.591971        100
>          | 4.9658285  5.1193873  5.0072705
>          |      5452       2102       7554
>          |
>     1999 | 25591.467  9586.1825  35177.649
>          | 72.749224  27.250776        100
>          |  4.613076  4.6748901  4.6297582
>          |      5265       1991       7256
>          |
>     2000 |  25067.72  9839.9109  34907.631
>          | 71.811576  28.188424        100
>          | 4.5186663  4.7986258  4.5942209
>          |      5163       2032       7195
>          |
>     2001 | 24673.646  9882.7968  34556.443
>          | 71.401001  28.598999        100
>          | 4.4476311  4.8195399  4.5480007
>          |      4983       1976       6959
>          |
>     2002 | 83751.067  30869.413  114620.48
>          | 73.068152  26.931848        100
>          | 15.096831  15.054075  15.085292
>          |     17682       6513      24195
>          |
>     2003 | 80686.437  27375.013  108061.45
>          |  74.66718   25.33282        100
>          | 14.544405  13.349963  14.222053
>          |     17002       5737      22739
>          |
>     2004 | 77406.999  26898.738  104305.74
>          | 74.211641  25.788359        100
>          | 13.953259  13.117698   13.72776
>          |     16052       5540      21592
>          |
>     2005 | 74552.231  27032.143  101584.37
>          | 73.389467  26.610533        100
>          | 13.438663  13.182755    13.3696
>          |     15263       5507      20770
>          |
>     2006 | 68720.522  26875.807  95596.329
>          | 71.886152  28.113848        100
>          | 12.387449  13.106515  12.581508
>          |     14234       5538      19772
>          |
>     2007 | 66760.785  26199.193  92959.979
>          | 71.816696  28.183304        100
>          |  12.03419  12.776551  12.234536
>          |     13813       5377      19190
>          |
>    Total | 554759.27  205056.85  759816.12
>          | 73.012306  26.987694        100
>          |       100        100        100
>          |    114909      42313     157222
> -------------------------------------------
>  Key:  weighted counts
>        row percentages
>        column percentages
>        number of observations
>
>  Pearson:
>    Uncorrected   chi2(9)         =   91.4953
>    Design-based  F(7.98, 25611.84)=    3.0966    P = 0.0017
>
> keep if year==1998|year==2007
>
> svy: tabulate year age2cat, count column row obs percent format(%10.0g) pearson
> (running tabulate on estimation sample)
>
> Number of strata   =        60                  Number of obs      =     26744
> Number of PSUs     =      1205                  Population size    = 131006.03
>                                                 Design df          =      1145
>
> -------------------------------------------
>           |             age2cat
>      YEAR |  <65 year   >=65 yea      Total
> ----------+--------------------------------
>      1998 | 27548.394  10497.654  38046.048
>           | 72.408029  27.591971        100
>           | 29.210724   28.60642  29.041449
>           |      5452       2102       7554
>           |
>      2007 | 66760.785  26199.193  92959.979
>           | 71.816696  28.183304        100
>           | 70.789276   71.39358  70.958551
>           |     13813       5377      19190
>           |
>     Total | 94309.179  36696.848  131006.03
>           | 71.988428  28.011572        100
>           |       100        100        100
>           |     19265       7479      26744
> -------------------------------------------
>   Key:  weighted counts
>         row percentages
>         column percentages
>         number of observations
>
>
>   Pearson:
>     Uncorrected   chi2(1)         =    0.9557
>     Design-based  F(., .)         =         .     P =      .
>
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