In this paper, we introduced a method of causal inference for arbitrary treatment regimes. We first expounded the generalized propensity score (Imai & Van Dyk, 2004) that extended the propensity score for binary treatments, and then causal inference with this generalized propensity score. Furthermore, we reanalyzed the data of relations between mass media and politics from a previous study, and discussed the usefulness of causal inference using generalized propensity scores.
