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st: RE: person-period data using prsnperd command


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: person-period data using prsnperd command
Date   Tue, 21 Nov 2006 15:19:33 -0000

Nick 
n.j.cox@durham.ac.uk 

> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu
> [mailto:owner-statalist@hsphsun2.harvard.edu]On Behalf Of Jinseok Kim
> Sent: 21 November 2006 15:09
> To: statalist@hsphsun2.harvard.edu
> Subject: st: person-period data using prsnperd command
> 
> 
> dear statalisters. 
> I created a person-period data set using prsnperd command to conduct a
> discrete time hazard model and found a potential error in the data set
> created. Here's the syntax I used:
>  
> . prsnperd childid minccage1 censored, t(72)
> No variation in event occurence for period 22!
> No variation in event occurence for period 32!
> No variation in event occurence for period 66!
> No variation in event occurence for period 68!
> No variation in event occurence for period 72!
>  
> If I understand correctly, _period variable created by prsnperd should
> have values ranging from 1 to 72 because minccage1, my length-to-event
> variable in the model, has a maximum value of 72. And here's what I
> found strange:
>  
> . tab _period if _period>72&_period<100, miss
>  
>     _period |      Freq.     Percent        Cum.
> ------------+-----------------------------------
>          73 |         12        3.86        3.86
>          74 |         12        3.86        7.72
>          75 |         12        3.86       11.58
>          76 |         12        3.86       15.43
>          77 |         12        3.86       19.29
>          78 |         12        3.86       23.15
>          79 |         12        3.86       27.01
>          80 |         12        3.86       30.87
>          81 |         12        3.86       34.73
>          82 |         12        3.86       38.59
> 
> *** I intentionally cut here to save the space...*******
>  
>          94 |         11        3.54       82.32
>          95 |         11        3.54       85.85
>          96 |         11        3.54       89.39
>          97 |         11        3.54       92.93
>          98 |         11        3.54       96.46
>          99 |         11        3.54      100.00
> ------------+-----------------------------------
>       Total |        311      100.00
>  
> . tab _period if _period>1000, miss
>  
>     _period |      Freq.     Percent        Cum.
> ------------+-----------------------------------
>        1001 |          1        0.20        0.20
>        1002 |          1        0.20        0.40
>        1003 |          1        0.20        0.60
>        1004 |          1        0.20        0.81
>        1005 |          1        0.20        1.01
>        1006 |          1        0.20        1.21
>        1007 |          1        0.20        1.41
>        1008 |          1        0.20        1.61
>        1009 |          1        0.20        1.81
>        1010 |          1        0.20        2.02
>        1011 |          1        0.20        2.22
>        1012 |          1        0.20        2.42
> 
> I like to hear from you all regarding whether I missed something while
> I use it, or it is a known glitch. Thanks.
>  
>  
>  
> Jinseok Kim, Ph.D.
> Assistant Professor
> College of Social Work
> University of South Carolina
> Columbia, SC 29208
>  
> Tel: 803-576-6082 
> Fax: 803-777-3498
> e-mail: jinseok.kim@sc.edu 
> 
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