Ezra Klein (vox.com) shows us Donald Trump's campaign to date in two charts.
The first chart shows a very high correlation between polling numbers and news coverage. Both have fallen off recently.
What's hard in all this is to separate correlation from causation. Is the media moving on from Trump because Trump's fortunes are dimming? Are Trump's fortunes dimming because the media is moving on? Was the media cause or effect of Trump's rise? Or both? It's hard to say.
One reason why it is difficult to conclude cause and effect it that some other variable might cause variations in both polls and media coverage. That's the "third variable" problem.
The second chart shows one possible third variable. Carson and Fiorina started to come up in the polls about the time Trump was going down.
Klein notes another possible third variable that could explain the polling results, the media coverage, and the rise of the other candidates.
As a card-carrying member of the media, it has certainly felt to me, starting around the second debate, that the limits of Trump's candidacy have come clearer: He's out of his depth on policy, his campaign is progressively less inventive and unusual, and fear of Trump is leading to consolidation around his most politically talented challengers — namely Rubio and Fiorina.
Trump is still chief clown, but if Klein is correct, the more press he gets the more he will be revealed as a braggart, bully, and BS-er and that would take him down more and would let other candidates (aka other clowns) get more attention in the polls and in the news. The thing is, "send in the clowns" is a good song but not very good election planning.
By way of apology to Judy Collins: Tucson Symphony Orchestra presents "An Evening with Judy Collins" on Friday, April 22, at 8:00 PM in the Tucson Music Hall. Track the TSO web site for announcements.