Slight discrepancy in popular-vote totals

[Kevin Nelson]

Right now, the Atlas has the 2016 popular-vote totals as Trump 45.94% and Clinton 48.03%.  But the supposedly "final" numbers from the Cook political report are Trump 46.10% and Clinton 48.19%.  Does anyone know why the discrepancy exists?  The Cook numbers come from back in January, so I suppose it's conceivable more votes could have been counted since then, but that seems unlikely. 

Looking at the numbers, I see the Atlas lists more third-party votes than the Cook spreadsheet does, by several hundred thousand.  At first I thought maybe the Cook numbers excluded write-in votes.  But a double-check showed that at least in some states, those numbers do include write-in votes.  I'm really not sure what's going on.  No one will get too excited over a discrepancy of 0.15 percentage points, but it would still be nice to get everything nailed down precisely.

(Incidentally, I'm in favor of abolishing the electoral college, and the slowness in getting precise popular-vote numbers is pretty frustrating from that perspective.  It doesn't make the case easier.  You can imagine what would happen if we had a direct presidential election and the popular-vote margin were within 0.1 percentage point.  Then people would get excited over this sort of discrepancy.  Very excited, indeed.) 

[SingingAnalyst]

There has never been such a thing as an official national PV total.

I'd imagine the two sources count write-ins, blank ballots, or spoiled ballots, differently.

[Kevin Nelson]

There may not be a single official national total, but each state is supposed to publish official results.  It should be straightforward to get a national total by adding those, and half a million votes should not just go missing.

I suspect the discrepancy does indeed have to do with write-in votes.  I only wish reputable sources like the Atlas and the Cook Report would be more transparent about their methodology.

[MarkD]

The FEC does have an official report of vote totals, state by state.

I think Atlas has over-counted the write-in votes by about 433,000 nation-wide. There is no difference between the vote totals that Atlas has compared to the FEC for the states of AL, AK, AR, CO, CT, DE, HI, IA, LA, ME, MD, MA, NE, NV, NH, NM, NC, ND, OK, OR, RI, SC, SD, TN, VT, WI, or WY. That's 27; a little more than half. I think Atlas goes the data at the county-level in order to include, among the votes cast, all of the write-in votes that the counties tallied but which the statewide election official did not tabulate.

I'll explain the difference between tally and tabulate, per what I just said. To tally simply means to count and report how many total write-in votes were cast. There were 100,000 write-in votes in the entire state. To tabulate means to report that, of those 100,000 votes, 22,000 were for Evan McMullin, 20,000 were for Bernie Sanders, 18,000 were for John Kasich, and so on. At the low end of the tabulation, there were some write-in votes for Pee-Wee Herman, Captain America, Darth Vader, and so on.

I'll use Missouri as an example. The largest counties, and many other smaller ones, have a count of all the votes cast, and that can be found online, such as here. Notice that it says there were 6,458 write-in votes, but it says to "See the official write-in report," which is here. About 3/4s of the counted write-in votes were invalid - 4828 - which is to say that voters wrote in names of people who were not "declared write-in candidates" -- in Missouri, only McMullin, de la Fuente, Hoefling, Kotlikoff, and Schoenke were "declared" candidates. Writing in names like Bernie Sanders or Jeb Bush gets your ballot treated as "invalid" in Missouri. But I think Atlas counted all of those invalid write-in ballots and included it in the total for Missouri. The Missouri SoS reported, to Washington D.C. (and hence, to the FEC), that the total number of votes cast was 2,808,605. Atlas added about 19,660 write-in votes that Missouri SoS does not include in the total, I assume because whomever did the research over-enthusiastically went to look at every single county's vote totals, disregarding the fact that those 19,660 were treated as invalid write-ins. I think Atlas has done that to a number of states.

[Seattle]

I believe then a good deal of them (~100,000) come from Washington where all write-ins are tallied, but none are tabulated unless the difference between the 1st and 2nd place candidates - Clinton and Trump in every county - is less than the count of over votes, under votes, and write-in votes. I think that applies to just Clark and Skagit Counties, and perhaps Whitman and Clallam too.