This function set is supplementary to 'MatchIt'. Its functions conduct several computations that 'MatchIt' does not provide. It takes the 'MatchIt' result object and/or the original data to compute standardized mean differences (SMD) between groups before and after matching. It also calculates ratio of variances and ratio of residual variances. In addition, it draws SMD comparison plots and QQ plots of distance measure score to help diagnose the matching result.