Re: conditional logistic regression

Posted by Rich Ulrich on Apr 01, 2021; 4:16am
URL: http://spssx-discussion.165.s1.nabble.com/conditional-logistic-regression-tp5740363p5740365.html

Either I don't understand the description, or you are

unnecessarily confusing in what you describe.  I don't see

anything that suggests a crossover design between two

different treatments (beyond that blunt mention of Xover). 

I don't see what sets up a conditional logistic.

The best I can figure out is that you have three data points

for "complication" (no, yes), which are at Times identified as

(Before, After1 and After2).  The "wide" layout should make it

easy to see how many cases are in an analysis - "Missing"

at any Time will drop a case for some analyses.

That layout does suggest simple tests using McNemar's test

for changes, between the sequential conditions. Or (maybe)

between Before and each After period.

I don't see a statement of hypotheses, or a mention of why

the design wanted two test periods.

I've read the posting at least three times after figuring out

my questions -- If I'm missing something, please let me know.

--

Rich Ulrich

---

From: SPSSX(r) Discussion <[hidden email]> on behalf of C_visser <[hidden email]>
Sent: Wednesday, March 31, 2021 4:55 AM
To: [hidden email] <[hidden email]>
Subject: conditional logistic regression

 

Dear everyone,

I am trying to use a conditional logistic regression in SPSS. I am using
SPSS version 25. I have looked at a lot of youtube videos explaining the
cox-regression method, but something is going wrong as it seems it is
censoring too many cases. I think this is due to our study design and
studied exposures, but I am not entirely sure (as I am just a beginner). Our
study design is the following:

We have participants with an certain exposure and want to compare their
measurements of certain values before the exposure and afterwards. In this
study they will receive this exposure two times. So we want to compare a
certain variable at the time before the exposure, the time between the first
and second exposure and after the second exposure. As we are measuring these
variables in the same subjects, we think we should use a cross-over design
and paired statics tests. Right now, I want to see if the subjects after the
first and second exposure have a higher risk of a certain complication
compared to before the exposure. An epidemiologist suggested using a
conditional logistic regression.

We have tried to do this test in spss by using the cox regression method. We
have coded a casecontrol variable (before exposure = 2, after exposure = 1)
as time, the depent variable as a categorical variable with 0 = no
complication, 1 = complication, timing as covariate (0 = before exposure; 1
= after exposure) and paired the measurement before and after exposure in
the same subject using an identical identifier. However, when I compare the
outcome with the mcnemar test it is not the same. Also it seems like spss is
running the test on a smaller number of subjects than I expected.

Can somebody help me with this problem?

Kind regards,

Chantal



--
Sent from: http://spssx-discussion.1045642.n5.nabble.com/

=====================
To manage your subscription to SPSSX-L, send a message to
[hidden email] (not to SPSSX-L), with no body text except the
command. To leave the list, send the command
SIGNOFF SPSSX-L
For a list of commands to manage subscriptions, send the command
INFO REFCARD

===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD