Hey, thanks for taking the time to respond.
By straight-party voters, does that mean they vote Republican down the whole ticket? If that were true, then negative values wouldn't be possible, right--since a slate vote would include a vote for Donald Trump. Positive values would come from split-ticket Democratic/Independent voters, and so the values could strictly be only positive.
Since Dr. Ayyadurai had a line of negative values as an acceptable case (Video 45:15 or so), I took the "straight-ticket" vote to mean "downballot Republican votes" so what he was saying makes the most sense.
Let me know if that's a misinterpretation though.