Dear dvwjr,
Nice job.
Two major problems, though.
The first is your attempt to correct the data for a particular ratio of R/D/I.
"Note the big dip in Republicans during the Democrat Convention."
"Now look at September, it swings the other way, now too few Dems and too many Republicans."
That is as it should be.
Party affiliation is not a static, unchanging demographic attribute like sex, race, or even religion (which can change, but not readily).
One ought to expect that during the Democrat convention, some number of people who would not ordinarily identify themselves as Democrats will so identify themselves as such. And vice versa for the Republican convention.
If you use R/D/I ratios from, say, the last election, you will distort the real outcome at the end of each convention, because some people who on THIS election day will identify as Republicans or Independents will identify as Democrats in the immediate aftermath of the Democrat convention, and conversely for the Republican convention.
It appears that Newsweek took that into account.
The second major problem (and not unrelated to the first) with your analysis is that it only corrects for party affiliation. How about for minority status? Or geographical location? Or sex? It may be that the pollsters tried to factor in these demographic attributes, as well.
Otherwise, nice piece of work.
sitetest
You wrote:
Party affiliation is not a static, unchanging demographic attribute like sex, race, or even religion (which can change, but not readily).
jvwjr addressed that here:
One of my assumptions that some might disagree with is that I feel that the political party affiliation sample composition should remain fairly consistent. Some believe that from month-to-month people re-identify with another party depending on how a particular candidate is faring in the polls. If that were so, then there would not have been any "Reagan Democrats" in the 1980s, they would have converted and become "Reagan Republicans". They may have voted for Ronald Reagan, but they still voted for Democrat congressional candidates, so to me they remain Democrats. I believe that party affiliation changes are slow, not detected nor truly documented by monthly fluctuations by polling organizations.
So his treatment of party affiliation is the result of a deliberate assumption rather than an oversight. In fact, if I've understood correctly, he considers this assumption to be a correction to Newsweek's results.
It takes decades to shift party affiliations. Don’t be fooled.