Statalist The Stata Listserver

[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

st: Date: Thu, 16 Nov 2006 13:37:35 -0500

From   "Visintainer, Paul" <[email protected]>
To   <[email protected]>
Subject   st: Date: Thu, 16 Nov 2006 13:37:35 -0500
Date   Thu, 16 Nov 2006 13:37:59 -0500 (EST)

Does anyone recall a command (similar to xtile or pctile) that creates a
new variable from an existing one, where the cutpoints are specific
percentages of the distribution?  (e.g., three groups created by
breaking the distribution at 37%, 62%, and 100%)

Paul F. Visintainer, PhD
Professor and Chair
Department of Epidemiology and Biostatistics
School of Public Health
New York Medical College
PH: (914) 594-4804
FX: (914) 594-4853
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Daniel Simon
Sent: Thursday, November 16, 2006 1:15 PM
To: [email protected]; [email protected]
Subject: Re: st: left censoring in discrete-time duration model

Austin - thanks for the response.  In fact, I have done what you
My point (3) where I said "I drop all observations from 1996 for firms
had websites" is actually what you are proposing, because once a firm
established a website (transitioned), they are excluded from the
sample thereafter.  I did not think about that when I wrote the
My apologies for not being clear. Thanks again for your response, which 
reminded me of what I was actually doing.

Moreover, as Austin says, I would also like to hear whether others also 
this is a sensible approach. thanks.


At 12:00 PM 11/16/2006 -0500, Austin Nichols wrote:
>Daniel Simon--
>It seems to me that your estimates can only apply to introductions
>("failures") after 1996, since you cannot distinguish pre-1996 and
>1996 introductions, and you should drop firms (in all years) that had
>websites in 1996, while keeping data on all other firms from 1996,
>though I would be interested to hear from someone who actually runs
>these sorts of models, e.g. Stephen Jenkins.
>On 11/16/06, Daniel Simon <[email protected]> wrote:
>>Hi - I'm using -hshaz- to estimate a discrete-time hazard model. I
>>some left censoring that I'm not sure how to deal with. I am looking
>>firms establishing websites. I can only observe the introduction of
>>websites from 1996 onwards.  However, I know that some firms
>>websites prior to 1996, but I'm not sure which ones. Currently, I have
>>tried three approaches: (1) Treat all firms that had a website in 1996
>>if they adopted in 1996 (the first year of the sample period), whether
>>adopted in 1996 or adopted earlier; (2) Exclude 1996 from the sample
>>the analysis with 1997); (3) Drop all observations from 1996 for firms
>>had websites.
>>All three approaches give me quite similar results, so it does not
>>that the censoring is a major issue. But, I'm wondering if there is a
>>better way to deal with it. Thanks. Daniel
>*   For searches and help try:

*   For searches and help try:

*   For searches and help try:

© Copyright 1996–2024 StataCorp LLC   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index