We were hoping for a special for our hundredth WitCH, but the chips fall when they fall. Still, it’s an odd one.
Robodebt is one of the greatest perversions of politics and public administration in Australian history. It is now reaching its appalling conclusion with the Royal Commission‘s hearings, a grotesque procession of half-wits, cowards and sociopathic goons. Rick Morton, and pretty much only Rick Morton, has covered the just-ended hearings in maddening and heart-rending detail. We only await Commissioner Holmes’s inevitably damning report.
We had pondering writing something on Robodebt, just to add our public declaration of disgust, and if only to employ the expression “Little Eichmanns”. But, we could see no natural angle. Now, however, a statistician has provided a different angle.
On Friday, statistician Noel Cressie had an article in The Conversation, titled,
Robodebt not only broke the laws of the land – it also broke laws of mathematics
It’s a cute, and obviously false, title, although a little flamboyance there is fine. But, what is Cressie getting at? Well,
The artificial intelligence (AI) algorithm behind Robodebt has been called “flawed”. But it was worse than that; it broke laws of mathematics. A mathematical law called Jensen’s inequality shows the Robodebt algorithm should have generated not only debts, but also credits.
Cressie creates a hypothetical example, and then considers this example in light of the Centrelink payment curve and Jensen’s inequality:
Because Will’s income was higher in 2019 and spread across the part where the payment curve is convex, Jensen’s inequality guarantees he would receive a Robodebt notice, even though there was no debt.
In 2018, however, Will’s income distribution was spread around smaller amounts where the curve is concave. So if Jensen’s inequality was adhered to, the AI algorithm should have issued him a “Robocredit” – but it didn’t.
Is there any sense or purpose to Cressie’s article? Make your judgment. Oh, and did we mention the Little Eichmanns?
Robodebt is not complicated. In brief:
1) At the instigation of government ministers, The Department of Human Services sought to recover overpayments from welfare recipients.
2) The primary method by which supposed overpayments were determined was by “income averaging”. So taking, for example, a person’s declared income for a year and dividing by 26 to give the person’s supposed fortnightly income. Then, if these “fortnightly incomes” indicated an “overpayment”, DHS has hit the jackpot and a debt notice is sent out.
3) The method was automated: the “robo” part of Robodebt.
4) If a person did not reply to the debt notice, or if they could not find work receipts or whatever to prove they were not overpaid, DHS took the debt to be valid and instigated proceedings for recovery.
5) DHS’s method for determining supposed overpayments was self-evidently bullshit. They all knew it.
6) The entire program was self-evidently immoral. They all knew it.
7) The entire program, which placed the burden of proof of innocence on the welfare recipient, was self-evidently illegal. They all knew it.
That’s about it, although there is at least one other thing to add. Robodebt was only permitted to continue for the insane number of years that it did because of the obsequious and trivialised and goldfish-memoried news media. The publishers and reporters who covered Robodebt like a forgettable football match rather than as the great travesty that it was are almost as culpable as the gargoyle ministers and DHS goons.
So, what does the “first rate statistician” Noel Cressie have to add? A little, and it is interesting enough. What Cressie is adding, however, is almost impossible to discern from his article.
The main mathematical point of Cressie’s article is illustrated by the second kink in the Cressie’s youth allowance curve, above. We’ve reproduced a version of that portion of the curve, below, with a few numbers and a straight line included to help with our explanation.
The graph indicates that if a person has earned $1000 in a given fortnight then they will receive an extra $100 benefit for that fortnight, and this benefit declines linearly, to zero when the earnings reach $1100. (Our numbers are approximate, but they will suffice.)
So, now imagine the person’s earnings over two fortnights, of $1000 and $1200. Then, on average, the person correctly receives a benefit of $50 per fortnight, indicated by the green dot. However, taking the person’s average earnings for the two fortnights, the Robodebt approach pretends the person has earned $1100 each fortnight, and thus is entitled to nothing for either week.
Our numbers are simple, but Cressie’s point is that Robodebt’s underestimate will always occur with the real numbers, as long as the incomes being averaged straddle the kink in the graph: the “benefit” determined by first averaging the fortnightly incomes will always be lower than the correct average benefit derived from the correct fortnightly incomes. In brief, the red dot will always be below the green dot.
Why does this happen? Because of the “convexity” of the benefit curve near the kink point, guaranteeing that the averaging line, the green line, lies above the benefit curve. This is what Cressie is referring to with “Jensen’s inequality”, a broad generalisation of this line-convexity property of no use here.
There’s more to Cressie’s article, some accurate, some weirdly off-base and all poorly presented, which can all be approached and understood in the same manner. It’s a bad article.
But at least Cressie is condemning Robodebt. Which, as should not be forgotten, ever, was bullshit and immoral and illegal. And they all knew it.