Through a combination of poor luck, poor policy, and poor performances, a sure thing had been shot-through with doubt. With unique access to voter research, Robb knew things were going south – and the longer the campaign lasted, the worse it got. The dud performances were human error. All campaigns have them. Hewson had struggled over the application of his GST to a birthday cake. More importantly, he'd insisted on public rallies which backfired when opponents heckled and orchestrated scuffles. The TV pictures conveyed a rancorous edge. But there was bad luck too. In Robb's estimation, an interview with a Canadian academic on the ABC's AM program two weeks out, had wrongly attributed a political crisis engulfing that country's prime minister to acrimony over a GST, rather than the North American Free Trade Agreement. Through this random event, he believes, a negative view of Hewson's GST became cemented every bit as firmly as the Liberal leader had welded himself to it. Rod Cameron, Labor's long-time pollster, also had access to both quantitative and qualitative data but they still pointed to defeat. As late as the final Monday, he thought Keating was toast. Yet in a stunning slap-down of the expert consensus, Keating prevailed six days later declaring it the "sweetest victory of all". For the first time in 30 years, a governing party had enlarged its majority in an election.

Could the conventional wisdom be wrong again? Not if betting markets are the oracle many now assume. They show Labor continuing to drift beyond $6.25. Pundits too, including this one, have looked at the maths and concluded a Labor win is supremely unlikely. Risking hubris, conservative Liberals are already dividing the spoils, pressing Malcolm Turnbull to "reach out" to his right wing by restoring Tony Abbott to the ministry. Peta Credlin, Abbott's doughty sidekick-turned-commentator, has also moved passed doubt stage declaring on Thursday of Bill Shorten: "I would say he is no longer running for the prime ministership but he's running to become, and stay, in the next term, leader of the opposition." All of this is based on the best data available of course and on proved experience in reading these things, which is not to be downplayed.

But no matter how instructive the history, nor how representative the data set, it is simply not predictive. Even with two weeks to go, the polling can be simultaneously accurate – as a contemporaneous snapshot of voter sentiment, and yet misleading, if misconstrued as the final word. That final word will be written in lead pencil by 15.67 million eligible Australians. In 2016, this is doubly important to remember in light of the high Rumsfeldian quotient of "known unknowns". Principal among these is Nick Xenophon. Seasoned campaigners on the ground in South Australia say the result there is impossible to predict with no precedent on which to draw. The scale of this "X-factor" wildcard is colossal. Not only could former frontbencher Jamie Briggs hit the fence in his safe 12.5 per cent Liberal jewel of Mayo, but Grey on 13.5 could fall as well. Christopher Pyne faces a genuine threat in leafy Sturt. Yet even with these colossal Liberal shocks, Labor might come away with no house gains (or worse), while trailing third in the Senate behind the Liberals with five senators and the eponymous Nick Xenophon Team with four. This horror scenario could leave Labor with just two senators giving it a combined return from the 18 senate spots up for grabs over the past two elections, of three. Utter humiliation. South Australia has been been one of Labor's safe places. Now it is unfathomable. For the first time since modern parties, it is likely that neither of the majors will secure 50 per cent of the primary vote in any lower house seat across the entire state. How this morass, the possible rout of up to four Liberals in Western Australia and other geo-political variations play out nationally, could yet determine the result of this election.

And that's without considering the game-changing potential of external "events" in the next fortnight over which nobody has control. Yes, the polls point to a narrow Coalition victory but either side could yet crash and burn. Loading If you listen to the campaign officials rather than the commentariat or the bookies (who are probably feeding each other anyway), that's exactly what they say. It ain't over 'til it's over. Mark Kenny is chief political correspondent.