On behalf of all Coxes everywhere, especially numero uno Sir David, I'd
like to request the spelling Cox regression.
Note that -spell- (SSC) is superseded by -tsspell- (SSC), but neither is
not applicable to wide format data anyway.
In this case, you can just concatenate your data into one string and
look for spells using -strpos()-.
egen wall = concat(w1-w48)
gen workspell = strpos(wall, "0000")
This will return the start week of the first such spell if there is one
and 0 otherwise.
Hence
gen byte success = workspell > 0
In general, however, you'd be better off after a -reshape- to long.
See also
SJ-7-2 dm0029 . . . . . . . . . . . . . . Speaking Stata: Identifying
spells
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N.
J. Cox
Q2/07 SJ 7(2):249--265 (no
commands)
shows how to handle spells with complete control over
spell specification
Nick
[email protected]
Morten Vejs Willert
In relation to performing a cox regression, I am looking for a way to
identify spells in a dataset containing longitudinal panel data of 48
week-by-week registrations on absenteeism from work.
The dataset is in wide format. For each participant(=id) there are 48
variables (one per week) containing either the value 0 (=working) or
the value 1 (=absent from work). The week-by-week variables are named
consecutively w1, w2, w3, ... w48, as illustrated below:
id w1 w2 w3 w4 w5 w6 ..... w48
1 1 1 1 0 0 0 0
2 1 0 0 0 0 0 0
3 1 1 1 1 1 0 0
4 0 0 0 0 0 0 0
...
102 1 1 1 1 0 0 0
I am interested in determining when a participant has had a spell of
four consecutive weeks working - so in my dataset I want to identify
spells of 4 consecutive 0's, when combing through the variable w1 to
w48 - and I want to generate two new variables: 'success' describing
if the participant has had such a spell (values 0 or1), and
'successtime' denoting the first week of the identified spells (values
1 to 45).
I have tried to use the command -spell- to achieve this, but with no
success. Does anyone have a solution to this problem?
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