Before revision:  We start by arguing that commonly used estimation procedures tend to ignore crucial time-series aspects of the data. Next, we develop a graphical tool and a formal test to illustrate the issues of the design using data from prominent studies in development economics and macroeconomic. Motivated by these studies, we construct a new IV estimator, which is based on the time-series model for the aggregate shock.
After revision:  We start by arguing that commonly used estimation procedures tend to ignore crucial time-series model. We use the unit weights to control for unobserved aggregate confounders and use the time-series model for the aggregate shock.