Hi Peter, That was my first port of call before I posted this thread. Unfortunately, it does not seem to explicitly state which test is used or how the p-value is calculated. Thanks, Rob. -- View this message in context: http://r.789695.n4.nabble.com/P-value-from-Matching-tp4703309p4703345.html Sent from the R help mailing list archive at Nabble.com.