To paraphrase Mark Twain: Reports of President Trump’s political death “are greatly exaggerated.” Simply scanning approval ratings overlooks the many trends determining a president’s effectiveness and re-electability. Many of these favor Mr. Trump. As his 100-day milestone passed, the president’s lagging approval ratings were frequently cited. Two major problems exist with this point-in-time comparative approach: the moment when it is taken and to what it is compared. Considering the uniqueness of Mr. Trump’s campaign and presidency thus far, applying conventional measures to the unconventional is questionable. Rather than choosing just a single sample, an average over time offers a better...