Recently Google has kindly made available a new open-source package for estimating causal effects in time series, using R.
Read the release announcement on Google’s Open Source blog. The package easily allows to measure the impact of an event (e.g. a marketing campaign) on a time-series of interest (e.g. online sales) by creating a counterfactual “synthetic control” by means of Bayesian statistics.
(For nerds: the technical explanation of the estimator is in the Research at Google website.)