I realize that "proving" things are difficult with post hoc parametric statistics. My view of TIA is that he is the "John Snow" of election pollsters (
http://en.wikipedia.org/wiki/John_Snow_(physician) ). Sometimes the "scientific" evidence is less compelling than the big picture. My original reason for joining DU and other groups was entirely anecdotal:
I witnessed a voting machine switching votes in a Clearwater, Fl election (for a Senate race: Betty Castor's votes would not record on the machine) and my wife and I both were asked to leave the polling area when we protested on the spot.
I saw unprotected machines stored at a local Florida library and had a battle with an election supervisor over the possible hacking of the machines.
I believe the American Statistical Association article in Chance magazine that concluded that the GOP actually lost a Senate race is correct (Christine Jennings), since it was an identical conclusion to my own analysis of the suspicious undervote.
I have witnessed missing mailed ballots and rejected mailed ballots on a number of occasions in Pinellas County, and follow up by voters is difficult after the official count is announced.
Recounts in Florida are a joke as we know - and the number issues similar to hanging chads, butterfly ballots, trashed voter machine tapes, and mail ballot mistakes happen so often that it would tie up courts for decades if the real number of complaints were followed up.
We have often seen reports of manipulation of voter registration rolls in Florida, and I have also seen illegal challenges to legitimate voters at the entrance to voting stations.
I have seen "impossible" results where tax referendums pass, Democratic local candidates win, and most voters appear to be registered Democratic voters, yet a GOP candidate will mysteriously win a federal election in some precincts (along with weird undervote or machine totals).
We have obviously had people come forward in Florida with accusations of writing software to hack the voting process.
If my admittedly personal observations are typical or repeated around the state and country (like in Oh, PA, and other reported trouble spots), you might infer that there is both polling and eyewitness evidence to suspect manipulated elections: the motive and opportunity were certainly there. Proving a legal case is pretty difficult without parallel elections, complete audits of voting and tabulating machines, or confessions of a guilty person. Also, some election supervisors and the Secretary of State (remember Harris!) are often intent on preventing fair observation of the process or gathering of evidence.
It is clear that researchers have demonstrated how machines can be hacked. If I were a person creating a formula to rig an election and had access to voting machine programming, I would set the parameters based on previously known voter registration variables and randomly switch or drop SOME votes on SOME machines and carefully STOP manipulating within a given machine or precinct if the predicted error variance was approached - thereby avoiding poll or statistical evidence that would clearly indicate manipulation. In other words, the results would almost always be within likely poll confidence intervals. If the election becomes so overwhelming that a candidate wins despite manipulation, the winner is correctly determined, but the results might appear skewed as TIA often reports as "recorded vs true" vote.
This does not prove what happened in several of the last three election cycles, but it is certainly logical to me given my own observations at local elections.