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Mathematician Says Big Data Is Causing a ‘Silent Financial Crisis’

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Re: Mathematician Says Big Data Is Causing a ‘Silent Financial Crisis’

#51
post #47

Earlier quoted context omitted.

But you don't train the algorithm to make the same decision humans did. You train it to maximize your objective function. I algorithmically trade the stock market. I don't train my model by asking whether it trades the way I would. The whole point is for it to do a better job than me! I train the model to maximize my returns [1] in backtests and simulations - if it trades differently than I do, so much the better! [1…

> But you don't train the algorithm to make the same decision humans did. You train it to maximize your objective function. In the idea case you would, sure. In practice mortgages take 25 years to deliver outcome data and the point isn't necessarily to get better outcomes, the mortgage provider would be content to get exactly the same outcomes (or even slightly worse outcomes) if it let them replace a large number of…

In most fields of human endeavor you do have an objective function better than "do what humans do".

Mortgages are very specifically an area where you do. First of all, there is historical data.

Second of all, you can backtest well before 25 years. A couple of weeks ago I wrote a blog post explaining specifically how to make measurements in the presence of delayed reactions - I'm discussing a situation involving sensor networks, literally the same mathematics would work for mortgage default or refinance: https://www.chrisstucchio.com/blog/2016/delayed_reactions.ht...

Third, mortgage lenders can often backtest alternate decisions because there are pretty straightforward relationships between decisions. Some of them are even mechanistic, e.g. refinance_risk(interest_rate) and default_prob(interest_rate) are monotonically increasing.

You seem to think we are living in the exact specific dark age necessary to make your morality play poignant and relevant. That's about as silly as Star Trek landing on all sorts of alien planets, each one designed to highlight one specific social issue from USA 1966.

Re: Mathematician Says Big Data Is Causing a ‘Silent Financial Crisis’

#52
post #45
post #40

> [algorithms] decide who gets access to credit and who pays higher insurance premiums, as well as who will receive online advertising for luxury handbags versus who’ll be targeted by predatory ads for for-profit universities. As opposed to what? Subjective decisions made by humans based on biases and personal preferences with no semblance of reason or fairness? > for example, who lives in an area targeted by crime f…

> the presence of more police actually confirms the fact that there is more of a need of police in this neighborhood? If we were to enforce all laws we would need massively more police in every neighborhood. When police are sent to flood a poor neighborhood they end up ticketing poor residents for a bunch of "violations" that they would also find if they went to the rich neighborhoods. But if they ever actually did i…

And how would you prove that hypothesis? With some data and an algorithm. The problem you speak of can be fixed by improving the model, not abandoning it.

Re: Mathematician Says Big Data Is Causing a ‘Silent Financial Crisis’

#53
post #24

Earlier quoted context omitted.

Here's an example, and the study cited here has been replicated in many American cities.[0] For the petty fines and eroded trust, this is from an advisory letter sent from the Justice Deparment to the judiciary of all fifty states: “Individuals may confront escalating debt; face repeated, unnecessary incarceration for nonpayment despite posing no danger to the community; lose their jobs; and become trapped in cycles…

Your link doesn't work.

http://www.nytimes.com/2012/06/29/nyregion/new-york-police-d...

This seems to be what he is referring to.

Re: Mathematician Says Big Data Is Causing a ‘Silent Financial Crisis’

#54
post #49

Earlier quoted context omitted.

What evidence do you have that one specific classification error resulting in a tweetstorm was the result of bias at all? I've been mislabeled as a tank in at least one image processing demo (admittedly, this was well before the era of deep learning). Image classification errors happen. Also, it's a bit strange that you suggest ML algos are racist against Asians. You do know that Asians are wildly overrepresented amo…

I did not make a blanket statement that all ML algos are racist against Asians. My point was to convey that if the training data do not accurately represent the population, the algorithm will carry the biases of that inaccurate representation: the algorithm is only as good as the data it is trained upon (for supervised learning). As a sibling comment stated, humans are deeply involved in all aspects of designing and…

I did not make a blanket statement that all ML algos are racist against Asians. My point was to convey that if the training data do not accurately represent the population, the algorithm will carry the biases of that inaccurate representation: the algorithm is only as good as the data it is trained upon (for supervised learning).

But that's not true. Inadequate training data will cause variance, not bias. This variance can have any direction.

In a linear prediction scenario (i.e. any go/no go decision process), which exactly what Cathy O'Neil is criticizing, the effect could just as easily be "more loans for black people" as "less loans for black people".

In a multidimensional predictor, it does directly decrease accuracy but that's all. "Black guy -> gorilla" is just as likely as "yummyfajitas -> tank".

Also, realistically, if we want to think about your black guy -> gorilla example, most likely if insufficient training data was the problem, then it was the number of gorillas that was too few. Google has vastly more black humans in their training set than gorillas - a quick google search suggests there are only 100,000 gorillas in the world, most of whom are probably unphotographed.

As a sibling comment stated, humans are deeply involved in all aspects of designing and interpreting an algorithm's results. To the extent that we are flawed, so will our algorithms be.

Sure, algorithms are flawed. But this does not imply that bias must be present proportionally to ours. Insofar as we do good statistics, human bias is mitigated and can even go away. Science works.

As a classical example, consider Morton's analysis of human skulls. Morton was a super racist guy trying to prove how white people are superior. But he did an unbiased analysis and accurately measured skull volume - filling a skull with buckshot is a pretty unbiased process.

http://journals.plos.org/plosbiology/article?id=10.1371/jour...

I am frankly confused as to what is so controversial about the statement that algorithms created by humans are not free from human biases.

What's controversial is that this is the idea of "original sin" but applied to science. And most of the proposed mechanisms are simply mathematically wrong. Also many of the examples cited by proponents of this original sin concept are also wrong.

Re: Mathematician Says Big Data Is Causing a ‘Silent Financial Crisis’

#55
post #40

> [algorithms] decide who gets access to credit and who pays higher insurance premiums, as well as who will receive online advertising for luxury handbags versus who’ll be targeted by predatory ads for for-profit universities. As opposed to what? Subjective decisions made by humans based on biases and personal preferences with no semblance of reason or fairness? > for example, who lives in an area targeted by crime f…

You jumped immediately to an assumption of higher crime in the neighborhood, while the article pointed out the existence of white-collar crime in other neighborhoods.

An interesting similar practical application was differential sentencing for drug dealing outside versus drug dealing inside. White and black Americans use illegal drugs at essentially the same rate, with white Americans pulling ahead in several categories historically. Suburban Americans more often deal drugs inside houses, while urban Americans are more likely to deal drugs outside than suburban Americans. Due in part to redlining practices, black people are more likely to live in urban areas and white people in suburban areas. So just send a bunch of cops to urban neighborhoods and you'll catch plenty of drug dealers and give them higher sentences, while letting all the white drug dealers go and giving them lower sentences if their behavior is egregious enough that you've got to arrest them.

This example doesn't even get into differential treatment for white-collar crime (scamming your investors) vs stealing meat from a grocery store. All those articles we saw on HN about scamming your employees and investors? MotionLoft, 1for.one? Those folks are "just doing business" and most commenters seemed to implicitly condone the scamming behavior -- sure it's unfortunate that it happens but you know business -- while no one here would condone stealing meat from a grocery store, and the meat-lifter would be more likely to get caught since there are cops at the doors of those grocery stores. Do we need cops in the startup scene if scams are happening, though?

The bad thing is not targeting "needs," as above, it's targeting perceived needs or exploiting differences in a way that contributes to injustice. I can see how you might not care about targeted advertising that allows you to ignore the lives of the poor -- that's fairly normal and in the US we really rely on it for political stability -- but ads that only show high-cost high-interest low-placement educational options for poor people push out ads from your local community college, targeted ads contribute to the political polarization we're seeing, targeted ads show higher-paying jobs to men than women regardless of qualifications. There is information asymmetry in a lot of these situations and in several ways: if the poor person trying to look up education doesn't already know about the low-cost legit CC and the information is buried after a page of for-profit ads, they may not understand all their options, and just as bad, we who earn a bit more may not know that's happening, because when we look up education to see if our teen could take multivariable calc nearby, we will get the CC right at the top of the page and the for-profit schools, not targeting us, won't show up! And then we can grumble with a clean conscience that poor people are so dumb they can't even look at the first search result...

Re: Mathematician Says Big Data Is Causing a ‘Silent Financial Crisis’

#56
post #40

> [algorithms] decide who gets access to credit and who pays higher insurance premiums, as well as who will receive online advertising for luxury handbags versus who’ll be targeted by predatory ads for for-profit universities. As opposed to what? Subjective decisions made by humans based on biases and personal preferences with no semblance of reason or fairness? > for example, who lives in an area targeted by crime f…

> So having more cops in a high-crime neighborhood is somehow a bad thing, because the presence of more police actually confirms the fact that there is more of a need of police in this neighborhood?

That's the essence of the Security vs Liberty argument. Yes, on one hand it is a good thing to have more security in an area which needs it; but will you accept say, being filmed 24/7 for more security, with the tradeoff that this same data can be analysed by third parties for any reason whatsoever (ala Minority Report's shopping mall scene).

It is not an easy problem and we must decide for ourselves which tradeoffs we will accept, because it is seldom free technology with no strings attached.

Re: Mathematician Says Big Data Is Causing a ‘Silent Financial Crisis’

#57
post #40

> [algorithms] decide who gets access to credit and who pays higher insurance premiums, as well as who will receive online advertising for luxury handbags versus who’ll be targeted by predatory ads for for-profit universities. As opposed to what? Subjective decisions made by humans based on biases and personal preferences with no semblance of reason or fairness? > for example, who lives in an area targeted by crime f…

I agree with you that for most of these points, the algorithm is unlikely to be less rational or more biased than a human (and the crime-fighting algorithm example doesn't seem to make a good point against the algorithm at all).

However, for something like a credit approval algorithm, there is a valid issue of centralisation - if there are problems with the algorithm, a large number of people will be affected negatively by the same algorithm. While humans are biased and imperfect, you can find some who are less biased, or call their manager and see if they can justify themselves, etc. I can imagine situations where it's hard to escape or find recourse when you're faced with an algorithm that's put you in an unfavourable situation.

I'm hoping that, given enough data to train on and enough validation to make sure they are working optimally, this will not really be a big issue, but I can understand if some people are concerned about that aspect.

Re: Mathematician Says Big Data Is Causing a ‘Silent Financial Crisis’

#58
post #47

Earlier quoted context omitted.

> But you don't train the algorithm to make the same decision humans did. You train it to maximize your objective function. In the idea case you would, sure. In practice mortgages take 25 years to deliver outcome data and the point isn't necessarily to get better outcomes, the mortgage provider would be content to get exactly the same outcomes (or even slightly worse outcomes) if it let them replace a large number of…

In most fields of human endeavor you do have an objective function better than "do what humans do". Mortgages are very specifically an area where you do. First of all, there is historical data. Second of all, you can backtest well before 25 years. A couple of weeks ago I wrote a blog post explaining specifically how to make measurements in the presence of delayed reactions - I'm discussing a situation involving senso…

There's no historical data on the default rates of people who didn't get mortgages, because they didn't get mortgages.

I'm willing to believe that theoretical solutions exist. I know from direct personal experience in the big data/lending industry that they are not always applied. If you are claiming that real-world lenders never train their models on human decisions then you are simply wrong.

Nice zinger - I hope you weren't saving it for too long. But I'm not going to get into witticisms or personal arguments.

Re: Mathematician Says Big Data Is Causing a ‘Silent Financial Crisis’

#59
post #40

> [algorithms] decide who gets access to credit and who pays higher insurance premiums, as well as who will receive online advertising for luxury handbags versus who’ll be targeted by predatory ads for for-profit universities. As opposed to what? Subjective decisions made by humans based on biases and personal preferences with no semblance of reason or fairness? > for example, who lives in an area targeted by crime f…

> So having more cops in a high-crime neighborhood is somehow a bad thing, because the presence of more police actually confirms the fact that there is more of a need of police in this neighborhood? Did you understand what you quoted? The author is saying that citations for petty offences (which practically everyone commits with some non-zero frequency, intentionally or not) have a higher chance of affecting future p…

> the Author isn't saying police are bad in general, rather that the negative effects of police presence are more significant in communities with higher police presence.

Yes, but are there any positive effects of police presence? Does this outweight the negative effects?

> The author is saying (assuming you think like them) that ignorance of suffering is a bad thing

So seeing poorly targeted ads tells you that people are suffering? It is the role of corporations to inform you that there are people who have different needs than you?

Re: Mathematician Says Big Data Is Causing a ‘Silent Financial Crisis’

#60
post #49

Earlier quoted context omitted.

I did not make a blanket statement that all ML algos are racist against Asians. My point was to convey that if the training data do not accurately represent the population, the algorithm will carry the biases of that inaccurate representation: the algorithm is only as good as the data it is trained upon (for supervised learning). As a sibling comment stated, humans are deeply involved in all aspects of designing and…

I did not make a blanket statement that all ML algos are racist against Asians. My point was to convey that if the training data do not accurately represent the population, the algorithm will carry the biases of that inaccurate representation: the algorithm is only as good as the data it is trained upon (for supervised learning). But that's not true. Inadequate training data will cause variance , not bias . This vari…

I appreciate your contribution to this discussion and will think about it further. Thanks.
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