IPTW for multiple treatment options I am dealing with a dataset which patients with 3 different types of treatment. Since the baseline characteristics are significantly different and biased, I need to match the baselines. However, the number of each group is too small to match using PSM.
I tried to use mnps and iptw functions of twang package, but I cannot join the two functions and failed to generate the new table 1.
How can I use iptw function with mnps?

Have you tried using WeightIt to generate the weights and cobalt to assess balance? WeightIt supports many methods to estimate weights for multi-category treatments, including generalized boosted models like in twang but also many other methods that you should try as well. cobalt provides balance tables and plots for multi-category (as well as binary and continuous) treatments. There is no reason to stick to twang unless you really like its functionality and know you want GBM.
