Hi. Using "psmatching" software into IBM SPSS Statistics, I analyzed the results of treatment of two groups of patients matched by the PSM method. The Log-Rank test was used to compare survival between two groups. I received the following comment from a statistics reviewer for a scientific journal: "In the PS matched sample, log rank test must be stratified by pairs to account for the paired nature of the observations. This is a fundamental concept in propensity score analysis." How can I perform his requirement (log rank test must be stratified by pairs to account for the paired nature of the observations) in IBM SPSS Statistics? The team of authors put a lot of effort into writing the article, but now we are in great difficulty and are afraid of losing all our scientific work. We will be very grateful for your answer on how we can implement the reviewer's requirement in practice