Wednesday, June 01, 2016

Please don't feed the weasels

OK, assuming that you've been keeping up with the general tone of political communication this year, you know that only one thing could make the Drudge Report happier than a picture of Hillary Clinton looking desperate (with some inept and nearly incomprehensible typography). That'd be a picture of Hillary Clinton coughing (with some inept and nearly incomprehensible typography). With that as a given, let's approach the problem from a different angle: Would the allegedly professional media please stop feeding the bottom-feeders?

Specifically, that'd be the Los Angeles Times piece linked to at Tuesday morning's Drudge homepage:

Hillary Clinton’s campaign had once hoped the California primary could be a coronation for the former secretary of State, the last major stop en route to claiming the Democratic presidential nomination.

Instead, it has turned into a dogfight with Bernie Sanders, who has been campaigning nonstop through the state. With at least one public poll showing the race now a tie, the Clinton campaign has decided to step up her appearances in the state.

Unless "public poll" means something other than "public opinion poll," or "publicly available poll" -- perhaps the Times could provide some data about the alleged poll that allegedly shows the alleged tie? Otherwise, we could fall back on the polls aggregated at Real Clear Politics, captured Tuesday morning around the same time:
Short answer, none of these five allegedly most recent polls* of the California Democratic primary show a tie. Two of them show Clinton leading by 2 points, which is not much of a lead -- it's fractionally better than even money that those differences match a real difference in the population, but you shouldn't bet on it unless randomly giving away money is your idea of a good time.**

Most of the other polls, including the one that apparently sat there for two weeks before Real Clear Politics knew it, show Clinton with a lead that is statistically significant at 95% confidence, meaning one chance in 20 that the difference in sample values doesn't reflect a similar difference in population values. The poll that doesn't is "within the margin of error," given that the "margin of error" applies to both points in the distribution," but is still almost certain to reflect a Clinton lead. Whatever "Cali" is, it is not "thisclose."

Does that mean we know who's going to win the California Democratic primary? No. Neither do you, and neither does the Los Angeles Times. It means we should be careful about how we interpret survey data.  Some things you should remember::
  • Any poll result might be an outlier
  • Then again, it might not
If I had to guess, meaning if I spread the results out and tried to estimate the range and midpoint of the results for Clinton and Sanders, I'd guess that the highest Clinton result might be an outlier -- meaning that of the 10 results shown in the crosstab, it seems the most likely to fall outside the normal distribution you'd expect if you drew several dozen random samples of likely California voters. But I don't know.

A corollary of that, of course, is that neither does the Los Angeles Times. What we know is that among the five results shown above, there are no ties. Of the two most recent results, one shows Clinton with a huge lead (which might or might not represent an outlier); the other shows a negligible lead (which also might or might not be an outlier).

You should at this point yawn and indicate that you're tired of polls. Fine. I'm tired of polls too, though I'm endlessly fascinated in how people make meaning out of them. My plea to the institutions that ought to know better -- the NYTs, the WashPosts, the LATimeses -- is to stop making pop fiction of them. Every time you guys turn out a fabricated drama from data that a well-trained undergraduate would question, you enable the genuine sleazebags like Drudge to do their thing.

Please stop. Please. Democracy is actually at stake.

* As of Tuesday evening, RCP was showing four polls: the top three above and one that was in the field May 4-16, of 694 likely voters, showing Clinton with 51% to Sanders' 38%. RCP does not provide a margin of sampling error for that poll, which should raise some doubt in your mind about RCP's general competence at reporting quantitative data. (The maximum margin of sampling error at 95% confidence for a random sample of n = 694 is -- who wants to be first in the comments?)

** Everybody has a hobby. 
*** Pay attention, FiveThirtyEight 

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