I apologize that I can't be completely explicit because this is for review of an unpublished article.
The design involved a cluster randomized trial of a new procedure to monitor an illness. Health care centers were randomly assigned to treatment or control. They were also matched on two relevant conditions - but there could be many other relevant factors. Then patients were followed.
For one continuous measure, the authors used a matched t-test. For survival, they used Cox proportional hazards but stratified by site pair and fit a separate model for each site pair, with a constraint of equal coefficients but different baseline hazards.
This seems intuitively wrong to me; this doesn't really seem like proper matching for a paired t-test and I don't really see how they can do Cox PH regression that way.
But I'm not certain, so I wanted to get thoughts from experts.
EDIT: The t-test was on an individual measure and the sites were randomized in pairs.