which data set is based on the parallel trend assumption? which of the following is true about propensity score matching? when does a trend change occur in each pre-period? how many treatments and control obs which data is comparable to the control obs how does a pattern score match a trend analysis why do we use propensity score matching what is the purpose of a trend assumption in stata what is the propensity score in dd how is parallel trend assumption in statistics used what is the propensity score for trending how to do pre period trend analysis when is a trend in a treatment or control sample when do you use a propensity score to predict trends in a controlled trial which condition is associated with the use of propensity score matching why would we use the parallel trend assumption for the outcome variable in a pre-period? what is the difference between a control and treatment obs what is parallel trend assumed when to use the propensity score in regression how to account for trends in propensity scores