It's pretty simple, actually. It's a big game of broken telephone.
Precincts report to whomever else at the state level, that gets reported to the public. There's a company called Edison that provides a live election-night feed of this information, collated, via their API.
The trouble is that that Edison feed is intended for exactly what you see - numbers on a news channel during live coverage. Well... they kind of cheaped out a bit.
The format of the data is something like this:
Total votes: 3,941,826
Biden: 56.6 (percent)
Trump: 42.0 (percent).
This makes it a bit smaller, easier to serve, when you have a lot of companies hitting your API repeatedly on election night. I don't know if it's actually meaningful, but it's a little something.
What is likely happening is that the TV channel does the math: 3,941,826 at 56.6% means we want to put 2 231 073.516 on the screen for Biden - round it up to 074.
The Edison API is rounding as well, to the nearest 0.1%. These rounding errors (and the fact that it's imprecise to start) can result in the appearance of votes disappearing or being deducted.
It can't be a rounding error because the discrepancies are larger than a rounding error could describe. An error of 0.1% is about 3000 votes, nowhere near the 17000+ flip.
The numbers that switch from Trump to Biden are exactly the same, which wouldn't happen if you're rounding values.
The values provided by Edison are different than what appears on the screen, so I imagine that the networks get the actual numbers but Edison only stores the percentages to save space.
An analysis by fishyPussy on another thread shows:
It's pretty simple, actually. It's a big game of broken telephone.
Precincts report to whomever else at the state level, that gets reported to the public. There's a company called Edison that provides a live election-night feed of this information, collated, via their API.
The trouble is that that Edison feed is intended for exactly what you see - numbers on a news channel during live coverage. Well... they kind of cheaped out a bit.
The format of the data is something like this:
Total votes: 3,941,826
Biden: 56.6 (percent)
Trump: 42.0 (percent).
This makes it a bit smaller, easier to serve, when you have a lot of companies hitting your API repeatedly on election night. I don't know if it's actually meaningful, but it's a little something.
What is likely happening is that the TV channel does the math: 3,941,826 at 56.6% means we want to put 2 231 073.516 on the screen for Biden - round it up to 074.
The Edison API is rounding as well, to the nearest 0.1%. These rounding errors (and the fact that it's imprecise to start) can result in the appearance of votes disappearing or being deducted.
There are 3 problems with your theory.
It can't be a rounding error because the discrepancies are larger than a rounding error could describe. An error of 0.1% is about 3000 votes, nowhere near the 17000+ flip.
The numbers that switch from Trump to Biden are exactly the same, which wouldn't happen if you're rounding values.
The values provided by Edison are different than what appears on the screen, so I imagine that the networks get the actual numbers but Edison only stores the percentages to save space.
An analysis by fishyPussy on another thread shows:
"PA:
Using data:
https://static01.nyt.com/elections-assets/2020/data/api/2020-11-03/race-page/pennsylvania/president.json
Before at time 2020-11-04T04:07:43Z
Trump: 0.566 * 2984468 = 1689208.888
Biden: 0.42 * 2984468 = 1253476.56
After at time 2020-11-04T04:08:51Z
Trump: 0.56 * 2984522 = 1671332.32
Biden: 0.426 * 2984522 = 1271406.372
New votes = 2984522 - 2984468 = 54
Trump's change: 1671332.32 - 1689208.888 = -17876.568
Biden's change: 1271406.372 - 1253476.56 = 17929.812"
https://thedonald.win/p/11QRkHpBIt/reminder-19958-pennsylvania-vote/c/
It could also happen if the total votes and percentages get out of sync for one data drop, then sync up the next one.