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Re: st: R: Stset-ing Multiple Failure/Multiple Spell Data : Moving in and out of risk set
From
Kathleen Bui <[email protected]>
To
[email protected]
Subject
Re: st: R: Stset-ing Multiple Failure/Multiple Spell Data : Moving in and out of risk set
Date
Fri, 18 Mar 2011 17:13:33 -0700 (PDT)
Thanks for all the help!
I do understand that smaller time intervals would be a much better , but I
don't have access to any smaller time frame than a year.
On another note,I was wondering, how do I go about "reseting" the time to zero
for each spell of self-employment, since I have multiple observations for each
spell of selfemployment? (If I wanted to employ the PWP time gap model approach)
For example, following my example before, if I had something that looked like:
(where the _spell, just indicates what spell of self-employment (first second
etc)),
How can I stset the data so the time is "reset" to zero for each new spell?
+----------------------------------------------------------------------------------+
PersonID Year0 Year Failed SelfEmploy _spell
-------------------------------------------------------------------------------------------
1. 1 . 1990 0 0 0
2. 1 1990 1991 0 1 1
3. 1 1991 1992 0 1 1
4. 1 1992 1993 0 1 1
5. 1 1993 1994 1 1 1
6. 1 1994 1995 0 0 0
7. 1 1995 1996 0 0 0
8. 1 1996 1997 0 1 2
9. 1 1997 1998 0 1 2
10. 1 1998 1999 1 1 2
-------------------------------------------------------
11. 1 1999 2000 0 0 0
12. 2 . 1993 0 0 0
13. 2 1993 1994 0 1 1
14. 2 1994 1995 0 1 1
15. 2 1995 1996 0 1 1
-------------------------------------------------------
16. 2 1996 1997 1 1 1
17. 2 1997 1998 0 0 0
+-------------------------------------------------------+
If I do:
stset Year, origin(SelfEmploy==1) failure(Failed) time0(Year0) id(PersonID)
exit(time .) if(_spell!=0)
this doesn't reset the time for the beginning of each spell, rather it continues
(with time gaps) from the time of the first spell.
Thanks again! Appreciate the help!
-Kathleen
The following example (performed in Stata 9.2/SE) considers this issue:
--------------- exampe begins ------------------------------------
set obs 6
g id = 1 in 1/2
replace id=2 in 3/4
replace id=3 in 5/6
g In=0
replace In=6 in 2
replace In=3 in 4
replace In=4 in 6
g Out=1
replace Out=7 in 2
replace Out=8 in 4
replace Out=5 in 6
g No_Self_Employed=1
replace No_Self_Employed=0 in 4
stset Out, id(id) failure(No_Self_Employed==1)time0(In)
exit(No_Self_Employed==2) origin(time In)
stdes
--------------- exampe ends ------------------------------------
In the previous code subjects do not live the SA at the first failure (ie
No_Self_Employed==1)- since it would conflate with the assumption of
multiple failures - but when the event No_Self_Employed==2 comes alive (and
this event will never occurr).
As I can see from your thread and previous replies, your subjects do show
gaps. You can check whether gaps are consistent with your methodological
expectations using - stdes -.
For more on this topic, I would refer you to:
MA Cleves, WW Gould, RG Gutierrez. An intoduction to survival analysis using
Stata. Revised edition. College Station: Stata Press, 2004: 59-62.The same
textbook (147-156)also offers interesting insights on Cox model with shared
frailty, that may fit your data;
the already referenced http://www.stata.com/support/faqs/stat/stmfail.html.
HTH and Kind Regards,
Carlo
-----Messaggio originale-----
Da: [email protected]
[mailto:[email protected]] Per conto di Kathleen Bui
Inviato: domenica 13 marzo 2011 16.31
A: [email protected]
Oggetto: st: Stset-ing Multiple Failure/Multiple Spell Data : Moving in and
out of risk set
My question is how to stset a multiple failure data set when an individual
can
move in and out of the risk set.
I have read Cleves’s An Introduction to Survival Analysis Using Stata,
Cleve’s
STB-49, and all previous posts concerning st-setting multiple failures.
Others
have asked similar questions as mine, but I have yet to find a solution that
works.
I am analyzing the duration of an individual’s stay in Self-Employment.
Failure
will be exit from self-employment. My question is how can I stset the data
so
that Stata recognizes that an individual can move into and out of the risk
set
(which is being Self-Employed).
To be more explicit, for each individual in my data set, I have information
as
to whether or not they are Self-Employed. The issue arises when an
individual
has a self employment history as follows:
The individual is self-employed and therefore at risk of failure. Then they
fail (leave self employment) and enter waged employment. By entering waged
employment, they are no longer at risk of failing, since they are no longer
Self-Employed. However, after a period of time, they once again become Self
Employed (thus re-enter the risk set) and fail once again (their second
failure).
As a result, multiple failures are possible as individuals are moving in and
out
of different employment states. However, although I understand that Stata
can
recognize multiple failures, I am unsure of how stset can be used to
recognize
the multiple spells of Self-Employment, particularly the period of time
between
spells when the individual is no longer at risk.
Specifically, I am unable to set the analysis time back to 0 for when the
individual begins a second period at risk after being not at risk.
For example, one individual in my data set of multiple individuals can look
like:
+----------------------------------------------------------------------+
| ID Year0 Year SelfEmploy Failure |
|--------------------------------------------------------------------|
1. | 1 1989 1990 0 0 |
2. | 1 1990 1991 1 0 |
3. | 1 1991 1992 1 0 |
4. | 1 1992 1993 1 0 |
5. | 1 1993 1994 1 0 |
6. | 1 1994 1995 0 1 |
7. | 1 1995 1996 0 0 |
8. | 1 1996 1997 1 0 |
9. | 1 1997 1998 1 0 |
10. | 1 1998 1999 1 0 |
11. | 1 1999 2000 0 1 |
+-------------------------------------------------------------------+
where “SelfEmploy” is the indicator variable denoting whether or not the
individual is self employed, “Failed” is an indicator variable denoting if
the
individual has left self employment and year0 and year are the corresponding
beginning and end of time period.
So between, 1990 and 1994, the individual is at risk of failing, and fails
between 1994 and 1995. But between 1995 and 1996, they are no longer at risk
of
failing (say they are employed in the waged sector). But then they enter
self
employment in 1996 and thus experience another failure between in 1999-2000.
Is there a command in stset that allows Stata to “ignore” the periods when
they
are no longer at risk?
For example, when I stset my data as follows: stset year,
origin(SelfEmploy==1)
failure(Failed) time0(Year0) id(PersonID) exit(time .), the period when
they
are no longer at risk of failing is treated as if they are in
self-employment as
the output I receive is:
+---------------------------------------------------------------------------
------------- +
| ID Year0 Year SelfEmploy Failure _s _d _t0 _t
|
|-----------------------------------------------------------------------
---------------------|
1. | 1 1989 1990 0 0 0 0
.
. |
2. | 1 1990 1991 1 0 0 0 .
. |
3. | 1 1991 1992 1 0 1 0 0
1 |
4. | 1 1992 1993 1 0 1 0 1
2 |
5. | 1 1993 1994 1 0 1 0 2
3 |
6. | 1 1994 1995 0 1 1 1
3
4 |
7. | 1 1995 1996 0 0 1 0
4
5 |
8. | 1 1996 1997 1 0 1 0
5
6 |
9. | 1 1997 1998 1 0 1 0
6
7 |
10.| 1 1998 1999 1 0 1 0 7
8 |
11.| 1 1999 2000 0 1 1 1
8
9 |
+---------------------------------------------------------------------------
----------------+
Stata seems to count the period form 1995-1996,as a time where the
individual is
at risk of failing, when he is not.
Therefore, am unsure as to how to st-set the data so that from 1995-1996,
Stata
recognizes that the individual is no longer at risk of failing and that my
analysis time can be “Reset” to 0 for when the individual begins a second
period
at risk after being not at risk.
Any suggestions?
Any help would be appreciated!
Thanks!!
Kathleen Bui
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