Does becoming President of the United States cause you to age faster than you would have otherwise, if you had not become President? Media sources have claimed that presidents age more quickly while in office. The British tabloid The Daily Mail asserted “American presidents age TWICE as fast while in office” (Daily …

This is a live document that is subject to updating at any time. Introduction This document, the first of a three part series, is an introduction to matching in R using the optmatch and RItools packages. We focus on unit-to-unit matching, as opposed to other recent approaches that focus on obtaining overall balance in …