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st: logistic regression to assume equal number of observations
From
"Delahanty, Ryan" <[email protected]>
To
"[email protected]" <[email protected]>
Subject
st: logistic regression to assume equal number of observations
Date
Tue, 19 Jul 2011 05:33:11 -0500
I have a case-control (cc) dataset of some 10,000 people (5,000 cases and 5,000 controls).
Each person has experienced up to 10,000 possible events.
Each event can have a state 0-4.
In addition, these people were collected at one of two different sites.
Some people have experienced more events than others (total_events).
Imagine the data takes this form:
Person cc event event_state site total_events
1 1 1 1 1 3
1 1 10 2 1 3
1 1 100 1 1 3
2 0 10 4 0 2
2 0 1000 3 0 2
3 1 100 1 1 1
Unique lines do not exist for all person-event combinations, just for instances where a person experienced the event (i.e. event_state!=0). I'm trying to carry out a regression of the using -logistic- (Stata/SE 11.0 Win 64-bit) using the following form in a do-file:
xi, prefix(): logistic cc i.event_state site total_events if event==1
xi, prefix(): logistic cc i.event_state site total_events if event==2
...
xi, prefix(): logistic cc i.event_state site total_events if event==10,000
For the most common events, I get a number of observations near 10,000 (i.e. everyone has experienced the event), but for most regressions my numbers will be between 2 and 10,000. My problem is that because having 10,000 entries for each possible individual-event combination would be prohibitively large (100M lines), I need to find an alternate way to run the above regression that will give me an identical result to what I would get if I ran a file of the size described, so that each regression has 10,000 observations. So for person 2 above, even though the event_state for event 1 would be 0, I want them included in the regression above (as with all people who would have event states of 0). How can I do this without including lines for all instances of event_state=0? Ideas about restructuring the data are also welcome so long as the equivalent regression could be run and the file does not become prohibitively large.
Sorry I'm not familiar with a common dataset to help better illustrate this point. Any help is appreciated.
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