Should credit scores be used for determining residency?

It's both exhilarating and frustrating when you see the warnings in papers you write play out in practice. Case in point, the proposal by DHS to use credit scores to ascertain whether someone should be granted legal residence.

Josh Lauer at Slate does a nice analysis of the proposal and I'll extract some relevant bits for commentary. First up: what does the proposal call for? (emphasis mine)

The new rule, contained in a proposal signed by DHS Secretary Kirstjen Nielsen, is designed to help immigration officers identify applicants likely to become a “public charge”—that is, a person primarily dependent on government assistance for food, housing, or medical care. According to the proposal, credit scores and other financial records (including credit reports, the comprehensive individual files from which credit scores are generated) would be reviewed to predict an applicant’s chances of “self-sufficiency.”

So what's the problem with this? What we're seeing is an example of the portability trap (from our upcoming FAT* paper). Specifically, scores designed in a different context (for deciding who to give loans to) are being used in this context (to determine self-sufficiency). Why is this a problem?

Unfortunately, this is not what traditional credit scores measure. They are specialized algorithms designed for one purpose: to predict future bill-paying delinquencies, for any reason. This includes late payments or defaults caused by insurmountable medical debts, job loss, and divorce—three leading causes of personal bankruptcy—as well as overspending and poor money management.

That is, the reason the portability trap is a problem is because you're using one predictor to train another system. And if you're trying to make any estimations about the validity of the resulting process, then you have to know whether the thing you're observing (in this case the credit score) has any relation to the thing you're trying to observe (the construct of "self-sufficiency"). And this is something we harp on a lot in our paper on axiomatic considerations of fairness (and ML in general)

And in this case there's a clear disconnect:

Credit scores do not predict whether an individual will become a public charge. And they do not predict financial self-sufficiency. They are only useful in this context if one believes credit scores reveal something about a person’s character. In other words, if one believes that people with low credit scores are moochers and malingerers. Given the Trump administration’s hostility toward (brown-skinned) immigrants, this conflation of credit scores and morality is not surprising.

And this is a core defining principle of our work: that beliefs about the world control how we choose our representations and learning procedures: the procedures cannot be justified except in the context of the beliefs that underpin them. 

I think that if you read anything I've written, it will be clear where I stand on the normative question of whether this is a good idea (tl;dr: NOT). But as a researcher, it's important to lay out a principled reason for why, and this sadly merely confirms that our work is on the right track.

What do I work on ?

So, what do you work on? 

As questions go, this is one of the most rudimentary. It's the conference equivalent of "Nice weather we're having", or "How about them Broncos!". It's a throat-clearer, designed to start a conversation in an easy non-controversial way. 

And yet I'm always having to calculate and calibrate my answers. There's a visible pause, a hesitation as I quickly look through my internal catalog of problems and decide which one I'll pull out. On the outside, the hesitation seems strange: as if I don't quite know what I work on, or if I don't know how to explain it. 

It's an occupational hazard that comes from living on the edge of many different areas. I go to data mining conferences, machine learning conferences, theory/geometry conferences, and (now) conferences on ethics, society and algorithms. And in each place I have a different circle of people I know, and a different answer to the question

So, what do you work on?  

It makes me uncomfortable, even though it shouldn't. I feel like I can only share a part of my research identity because otherwise my answer will make no sense or (worse!) seem like I'm trying to impress people with incomprehensible words. 

I don't doubt that most people share some form of this feeling. As researchers, none of us are one-dimensional, and most of us work on many different problems at a time. Probably the easiest answer to the question is the problem that one has most recently worked on. But I sense that my case is a little unusual: not the breadth per se, but the range of topics (and styles of problem solving) that I dabble in. 

So, what do you work on? 

I often joke that my research area is a random walk through computer science and beyond. I started off in geometry, dabbled with GPUs (alas, before they were popular), found my way into information theory and geometry (and some differential geometry), slipped down the rabbit hole into data mining, machine learning, and a brief side foray into deep learning, and then built a nice little cottage in algorithmic fairness, where I spend more time talking to social scientists and lawyers than computer scientists.

Being an academic nomad has its virtues: I don't really get bored with my work. But it also feels like I'm always starting from square one with my learning and that there are always people who know way more about every topic than I do. And my academic roamings seem to mirror my actual nomadic status. I'm a foreigner in a land that gets stranger and less familiar by the day, and the longest time I've spent in any location is the place I'm in right now.

So, what do you work on? 

Maybe, in a way that's so American, "What do you work on" is really a question of "Who are you" in the way we bind together our work and our identity. When my students come and ask me what they should work on, what they're really asking me is to tell them what their research identity is, and my answer usually is, "whatever you want it to be right now". It's a frustrating answer no doubt, but I feel that it lowers the import of the question to a manageable level. 

So, what DO you work on?

I do algorithmic fairness, and think about the ethics of automated decision-making. I bring an algorithmic (and geometric) sensibility to these questions. I'm an amateur computational philosopher, a bias detective, an ML-translator for lawyers and policy folk, and my heart still sings when I see a beautiful lemma.