[HN Gopher] 'Simple' AI can anticipate bank managers' loan decis...
       ___________________________________________________________________
        
       'Simple' AI can anticipate bank managers' loan decisions to over
       95% accuracy
        
       Author : Hard_Space
       Score  : 89 points
       Date   : 2022-02-19 05:49 UTC (17 hours ago)
        
 (HTM) web link (www.unite.ai)
 (TXT) w3m dump (www.unite.ai)
        
       | throwaway81523 wrote:
       | How does "simple AI" compare with an old fashioned small table
       | lookup and a few "if" statements?
        
         | google234123 wrote:
         | https://en.wikipedia.org/wiki/Random_forest
        
           | ninjinxo wrote:
           | https://en.wikipedia.org/wiki/Expert_system
        
             | DrRavenstein wrote:
             | Difference is that random decision forests learn the rules
             | for themselves, they don't have to be programmed in
             | manually by experts. They're one of the most performant
             | "pre-deep-learning" machine learning models and a sensible
             | baseline for many ML tasks before you go out and buy a
             | $1500 GPU
        
               | Closi wrote:
               | The ability to program approval rules and understand why
               | decisions have been made (and then tweak the ruleset
               | based on economic/statistical analysis) is a feature for
               | these sort of organizations, not a limitation.
               | 
               | There will be elements of AI which are useful, but
               | ultimately banks will want to know _why_ a certain
               | decision was made, and want to incorporate their own
               | economic calculations and forecasts into the model.
        
               | visarga wrote:
               | Decision forests don't provide that explainability
               | though, how can you interpret averages of hundreds of
               | decision trees?
        
         | bob1029 wrote:
         | In my experience, many financial products marketed as having
         | "intelligence" are indeed just layers of SQL queries (rules).
         | 
         | The benefit of using SQL rules engine in a financial setting is
         | that you can prove causality and intent throughout. Why a
         | customer was declined for a loan can always be traced
         | deterministically to some rule SQL that legal previously
         | approved per regulations in that jurisdiction.
        
         | woadwarrior01 wrote:
         | Decision trees (the base learner in random forests and gradient
         | boosted decision trees) are effectively nested "if" statements,
         | and predictions from tree ensembles (RF and GBDT) are
         | effectively averages of predictions from those nested "if"
         | statements.
        
       | hooande wrote:
       | This isn't surprising. Most 'AI' comes down to correlating a
       | small number of variables (one or two) with a prediction target.
       | The real benefit of any form of machine learning is detecting
       | functional relationships between variables (ie, "when this AND
       | NOT that OR this"). It's just that these relationships don't
       | provide a real benefit in 99/100 real world use cases.
       | 
       | In the case of a loan, if the credit score is high they'll
       | probably qualify. If it's low, they won't. All other variables
       | are very minor in comparison to this one, which already
       | encapsulates almost all of the relevant information. This is by
       | far the most common situation for practical machine learning.
        
         | roenxi wrote:
         | Yes. But there is also an interesting failure mode - people
         | don't bother applying if they don't think they'll get accepted.
         | So presumably even just a "YES" will be a fairly good model of
         | what actually happens without necessarily capturing the real
         | model that the bank is using. A 95% accuracy rate isn't
         | necessarily very good because of this effect (it might be, it
         | just isn't certain).
        
           | sdoering wrote:
           | My SO used to work in a bank in the business loan securities
           | back office. Believe me. Lots of people and businesses apply
           | even if they themselves see no realistic chance of receiving
           | a loan.
           | 
           | And in private non business customers there are even a
           | significant amount that have less than nothing to their name,
           | living of welfare and still don't see, why they should not
           | receive a loan from the bank for the newest iPhone. Or a new
           | car. Or TV because "football's coming home".
           | 
           | Excuse my snarkiness, but the stories she told me from her
           | apprenticeship in the bank, when she was customer facing were
           | not painting a good picture of humans (Btw. well off or not).
           | But that is probably the case in any consumer facing job.
        
             | jacquesm wrote:
             | Excuse _my_ snarkiness, but having actually worked for a
             | bank and seeing the inside of the loan department from an
             | IT perspective, the bulk of that translates into: banks
             | will allow the people that are already wealthy to leverage
             | to make them even more wealthy while working hard to keep
             | those already down firmly in their place. Not to mention to
             | take advantage of them by charging them exorbitant fees for
             | the little bit of credit that is extended to them.
        
               | User23 wrote:
               | Since you have industry experience how would you have
               | banks rectify this perceived injustice? I can't conceive
               | of an underwriting process worthy of the name that isn't
               | going to consider those borrowers with collateral more
               | creditworthy than those without.
        
               | djbusby wrote:
               | For one, overdraft fees should only be charged once per
               | calendar month, not for every overage.
               | 
               | Also, the burden on the bank for an overdraft is near
               | zero, so why is it $35 for the customer? Perhaps a fee of
               | only $5 would be less regressive?
        
               | User23 wrote:
               | I don't know if it's still the case, but it used to be at
               | least some US banks would order pending transactions in
               | descending order of amount to maximize overdraft fees.
               | For example, if you had $100 in your account and had
               | charges for $1, $1, $1, $1, and $100 then as a
               | "courtesy"[1] the bank would clear the $100 and then
               | charge $35 times 4 for the remaining transactions.
               | 
               | Anyhow that's really awful and needs to stop, but I don't
               | see eliminating overdraft fees making a real dent in the
               | advantages wealthy borrowers have.
               | 
               | How could underwriting be changed to identify truly
               | creditworthy borrowers who don't have any financial or
               | real assets? We already know that simply lowering
               | underwriting standards has problems.
               | 
               | [1] Their words, not mine.
        
               | skybrian wrote:
               | Yeah, that's a very high-interest loan.
        
               | sdoering wrote:
               | I am with you. Shitty entitled customers calling female
               | tellers whores that need to be f**ed to loosen up a bit
               | (happened more than once) do not absolve banks from their
               | abysmal policies. Or the system that not only enables but
               | sometimes regulates/necessitates these policies.
               | 
               | I am not siding with banks in general here. I was just
               | exemplifying one aspect to show how it is not always
               | black and white.amd how there can be unreasonable
               | customers.
               | 
               | [Edit typos]
        
             | mvc wrote:
             | > why they should not receive a loan from the bank for the
             | newest iPhone
             | 
             | Excuse _my_ snarkiness but as someone who 's been poor and
             | needed a phone, I'd have got a loan to buy a 2nd hand phone
             | if anyone would've given me one. Trouble is, both the
             | companies providing the phones, and those providing the
             | loans seem to prefer that I get the brand new one.
        
               | sdoering wrote:
               | I am not talking about reasonable needs here. I am
               | talking about people who are Cleary feeling entitled to
               | receive loans they know the can never repair and would
               | not even be willing to try.
               | 
               | I myself had to live on 345 Euros a month for quite some
               | time. And even longer was living below what Germany
               | considers the amount of monthly income that one would
               | qualify to not be called poor ("Armutsgrenze"). I know
               | the feeling and hear you. The only difference is that I
               | could not even get a contract as no telco would find me
               | creditworthy enough. Needed to do prepaid and see how I
               | would get any old mobile.
        
         | kqr wrote:
         | Yup. This has been shown over and over by Meehl and that gang.
         | 
         | > The real benefit of any form of machine learning is detecting
         | functional relationships between variables (ie, "when this AND
         | NOT that OR this"). It's just that these relationships don't
         | provide a real benefit in 99/100 real world use cases.
         | 
         | And the real problem with humans, ironically enough, is that
         | due to narrative fallacy, confirmation bias, etc., humans
         | vastly overvalue the contributions of these special
         | circumstances.
         | 
         | If a dumb 2--3 variable rule predicts your friend will go to
         | the movies in the weekend, you are likely to go, "Yeah, maybe.
         | But she complained of that headache this morning, maybe there's
         | something deeper there that also makes them not want to go to
         | the movies."
         | 
         | In most cases, you'll be wrong to override the dumb rule.
         | 
         | So why do people do this? Well, the original movie-going
         | prediction might only have been a 55 % shot. So 45 % of the
         | time, your friend won't go to the movies, headache or not. But
         | if they don't, you'll think you made the right call considering
         | that headache.
         | 
         | If they do go, you'll end up thinking, "Right, of course. They
         | had the headache but their friend really wanted to go so of
         | course they would endure it."
         | 
         | In other words, you'll think of a way to frame your incorrect
         | call as the right one. (Hindsight bias.)
        
         | sdoering wrote:
         | When dealing with stakeholders in big corporations I learned
         | that they absolutely needed AI, machine learning and data
         | science as capabilities in the projects that they started. Even
         | if data was only very tangentially related to the core
         | product/project. If so, for example one needed to datascience
         | the shit out of project metadata to create a project efficiency
         | self optimization loop. Or what ever crap one could come up
         | with.
         | 
         | Else they would not be able to secure funding for the idea from
         | upper management because they had learned that 'data is the new
         | oil'.
         | 
         | The second VS part always needed/needs to be how this project
         | enables the product to be (or become) a platform where the
         | company can the run value added services on top (value adding
         | for the company, not the customer).
         | 
         | Imagine a car being a platform and you can book additional
         | horse power for the upcoming trip. Or change the background
         | image for the instrument panel. Or pay extra to natively have
         | access to your Spotify playlists. And then datascience the user
         | data to recommend even more stuff resulting in $$$ (by
         | imagination from management and fuelled by slide decks created
         | by some junior strategists that have never even owned a car but
         | presented by the client account lead in a lush retreat).
        
           | IgorPartola wrote:
           | I am unclear as to whether what you are saying is that they
           | need data science to justify their projects because when they
           | say that an AI told them that they need $X extra for the
           | project it carries more weight than when they say they did
           | the analysis by hand or if the data science actually provided
           | value in this case.
        
             | sdoering wrote:
             | No. They need AI in their projects to receive management
             | buy in (and funding) because management swallowed the hook
             | and now wants everything AI & data driven (even if it makes
             | no sense) to be able to brag to other managers from the
             | competition and other industries that they now use AI and
             | are a data driven company.
        
       | DrRavenstein wrote:
       | This headline and article are horrible and misrepresent the
       | problem and the outcome.
       | 
       | The paper is about the manual process of re-assigning a credit
       | score on a scale of 1 to 15 based on other customer criteria.
       | Really the fact that this process exists at all shows that their
       | initial credit scoring approach is flawed or too simplistic. The
       | argument of "just replace it with an if statement" does not hold
       | up in this scenario.
       | 
       | So this is not a "if number big lend. If number small no lend"
       | problem. Its a 15 way multi-class classification problem. They
       | even give a baseline for what happens if they randomly pick or
       | always pick the biggest class in the paper
       | 
       | > As is typical in machine learning we also report the Accuracy
       | p-value computed from a one-sided test (Kuhn et al., 2008) which
       | compares the prediction accuracy to the "no information rate",
       | which is the largest class percentage in the data (23.85%).
       | 
       | So yeah, 95% is somewhat better than 23.85%.
       | 
       | I agree with the general sentiment that is is likely a fairly
       | straight forward problem to predict if you are familiar with the
       | bank's operating procedures as there is no way these individuals
       | are making their own risk models and independent decisions. They
       | are there to follow the rules and provide human accountability.
       | 
       | An error analysis on the items the model couldn't predict would
       | definitely have been most interesting.
        
         | edmundsauto wrote:
         | Plus, systemic risk of a repeatable exploitation is more likely
         | without humans in the loop. Making a bad loan for $1M is bad,
         | but if "attackers" can repeatedly prove until they get a bad
         | risk $1B loan, it becomes business shattering.
        
           | visarga wrote:
           | Do they remove the human in the loop? That doesn't seem like
           | a smart idea. A model would be good just for suggestions.
           | 
           | Humans are both biased and with high variance (not to mention
           | corruptible), but the algorithm can benefit from much better
           | scrutiny and ensure uniform application of the criteria. If a
           | human overrides, then they got to have a good reason.
        
       | jakey_bakey wrote:
       | "Heuristics that work 95% of the time"
        
       | throwthere wrote:
       | I mean Zillow's valuation platform that bought homes had great
       | accuracy. We all know how that turned out-- Zillow ended up
       | buying a whole bunch of houses for much more than they were
       | worth. Such as the fate of recommender systems operating an
       | auction markets with humans who know better.
        
       | jokethrowaway wrote:
       | I really wish we would stop calling this AI.
       | 
       | I understand startups need funding from VCs whose idea of
       | technology is "BLOCKCHAIN AI" but, being interested in AI, the
       | amount of spam I have to dig through to find actual AI work is
       | insane.
        
         | shadowgovt wrote:
         | What does actual AI work look like these days?
        
           | anaganisk wrote:
           | If key==0: print("its zero") else: print("here is your 10 sec
           | un-skippable ad")
        
       | forgingahead wrote:
       | minimum_credit_score = Loan.joins(:borrower).where("loans.default
       | = true").average("borrowers.credit_score")
       | 
       | if loan_applicant.credit_score > minimum_credit_score
       | decision = "approve"
       | 
       | else                 decision = "reject"
       | 
       | end
        
         | zwaps wrote:
         | Would a linear decision barrier not be fit by the logistics
         | model?
        
         | ant6n wrote:
         | You want to use the average credit scores of all defaulting
         | loans as threshold? That seems really low, you're setting your
         | bank up for a lot of defaults. But then there's a lot of
         | selection bias in your data -- presumably your bank has been
         | denying loans to people with bad scores, so over time you your
         | minimum credit score is the upward inching average inside the
         | cracks between safe and denied loads.
        
           | sokoloff wrote:
           | It depends heavily on the interest rate as well. If the
           | interest rate is high enough, you can show a profit even with
           | a fair number of loans sent to collections.
        
       | lordnacho wrote:
       | I had a look at LendingClub data and indeed unsexy RF and GB were
       | pretty good. This shouldn't surprise us though, because what are
       | the likely predictive features other than how much the person
       | makes compared to what they want to borrow? Sure, there's what
       | they intend to do with it, perhaps adjustments as well for how
       | high their income is relative to where they live. All things that
       | a model can help quantify, but nothing terribly surprising
       | either.
       | 
       | What's left is a bit of judgement as to whether an applicant is
       | temporarily showing wrong data, eg if they're a student starting
       | their first job, what is their income, low or high? But basically
       | it means the bulk of cases can be done by machine and the loan
       | officer looks at some corner cases.
       | 
       | Note this person is also an actual person, i.e. capable of being
       | held to account. I once worked with a prime broker who decided to
       | waive the red flagged checks on a certain client in order to win
       | the business. The guy blew up badly, the bank lost money, and he
       | lost his job.
        
       | mjburgess wrote:
       | Accuracy is almost never the right statistic. Here,
       | _profitability_ is. As soon as you realise the target statistic
       | applies a human-goal-value-weighting to the prediction outcomes,
       | it should be easier to see why ML systems are often unsuited to
       | the task they 're set.
       | 
       | Here, those 5% of cases are likely business-ending or business-
       | making: precisely because they arent naively routine.
        
         | kqr wrote:
         | I think you can be even bolder: accuracy _never_ matters. It 's
         | always about the consequences, not probabilities. Sometimes the
         | two are the same, but most of the time they are not.
         | 
         | Also worth noting that the arithmetic expectation is only a
         | good way to measure the profitability if we are talking about
         | small amounts compared to your total wealth. For any other
         | case, you should use the geometric expectation of total wealth
         | to evaluate options. (This is equivalent to maximising log
         | wealth, the Kelly criterion.)
        
           | yobbo wrote:
           | Outcome * probability = expectancy, which is the quantity
           | usually maximised or minimized in AI.
           | 
           | The problem in this case was defined as reproducing the human
           | scores. Mainly, it's a demonstration of the information
           | content in the data and the scores. To me, it demonstrates
           | how simplistic the human scores are.
           | 
           | With information about historic outcomes, we could have
           | compared the effectiveness of the "credit score method" with
           | some other AI algorithm that was optimizing total value.
        
             | kqr wrote:
             | One little expansion: what you described first is the
             | arithmetic expectation, which is a good approximation when
             | the numbers involved are small compared to total wealth.
             | 
             | When you start taking larger bets, you want the geometric
             | expectation of total wealth, i.e. (current wealth +
             | outcome)^probability.
             | 
             | (This is the Kelly criterion for judging significant
             | opportunities.)
        
       | lngnmn2 wrote:
       | Because this is a trivial problem reducible to an n-dimension
       | vector.
        
       | richardfey wrote:
       | If you want to impress me, tell me also the results of these:
       | 
       | - Performance against a fair dice - Performance against a group
       | of humans trained to predict bank managers' loan decisions
        
         | jdrc wrote:
         | i d be more interested if the ai made a better financial
         | decision than the managers
        
         | DrRavenstein wrote:
         | The article is a bit rubbish. They're not predicting on the
         | binary "would we give these people a loan or not" but they're
         | predicting manual corrections fo credit scores by bank
         | managers. It's a 15 way classification problem (1 is low score,
         | 15 is high). The data is distributed in a bell-curve like way
         | with the most people in the 6 or 7 bracket.
         | 
         | From the paper:
         | 
         | > As is typical in machine learning we also report the Accuracy
         | p-value computed from a one-sided test (Kuhn et al., 2008)
         | which compares the prediction accuracy to the "no information
         | rate", which is the largest class percentage in the data
         | (23.85%).
         | 
         | So fair dice 23.85%, model 95%.
         | 
         | That said I bet a human who had read the banking rules and
         | regulations and recommendations on lending could easily match
         | this performance.
        
       | Brian_K_White wrote:
       | Title is oddly framed. What is interesting or useful about merely
       | not-quite predicting what a human will do?
       | 
       | Do the AI's 5% discrepency picks perform better or worse than the
       | human's picks?
       | 
       | The title is worded to suggest the AI can, or is very close, do
       | the human's job, which could totally be so.
       | 
       | But it could also be that the AI loses 5% vs the human, and the
       | bank only makes 5% on loans in the first place, and so losing 5%
       | of them is like totally erasing the entire income of the bank
       | (from loans) which makes the AI a complete Hindenberg, rather the
       | opposite of the implication from the title.
        
         | jsemrau wrote:
         | It takes a long while to validate this statistically though as
         | default cohorts move through the lending cycle.
        
         | Closi wrote:
         | Absolutely! There is not enough data here to signify the actual
         | performance of the algorithm.
         | 
         | Without more data it's not clear if the algorithm is actually
         | effective - e.g. if the approval rate of these loans is 80% for
         | instance, a formula of "always return true" could be said to be
         | '80% accurate compared to human decisions'.
         | 
         | And if the AI makes the same decisions as a human 95% of the
         | time, but then makes horrific errors the other 5% of the time,
         | it wouldn't be an appropriate replacement for the human. This
         | is the same issue with self driving - it doesn't matter if you
         | make great decisions 99% of the time if 1% of the time you
         | decide to drive into a wall (until you have got your error down
         | to a place where it's safer on aggregate than a human).
        
         | kqr wrote:
         | Given the research by Meehl, if there's a decent numeric rule
         | and a human decision that are closely predicting each other, my
         | money would be on the numeric rule being slightly more
         | accurate.
        
       | citizenpaul wrote:
       | If you spend 5 minutes in a bank this is not surprising. Probably
       | 99.99999% of most banking loan staff have zero input on if a loan
       | is accepted or not. They just follow the rules set from on high
       | and tell you yes or no to your face instead of a computer. Their
       | job is really just to calm you down when you get rejected or tell
       | you what you have to do to get accepted from their secret rules.
       | 
       | I even worked on a loan program years back to centralize a bunch
       | of acquired banks. They literally told their staff not to tell
       | customers there was nothing they could do and a set of rules in
       | the computer made 99% of the decision for the loans now.
        
       | Flip-per wrote:
       | As bank I'd look into these 4.x % of loans where the machine
       | learning disagrees. This headline feels like 20 years old though,
       | except for calling it "AI".
        
       | Ekaros wrote:
       | Loan decision is relatively straightforward algorithmic process.
       | I see no reason why AI is needed or wouldn't give similar
       | answers.
        
         | platers wrote:
         | Shouldn't the sentence be flipped in that case? I see no reason
         | why expensive human is needed or wouldn't give similar answers.
        
           | toomanydoubts wrote:
           | The point is that it can be solved with simple algorithms. No
           | expensive human nor AI needed.
        
             | Ekaros wrote:
             | Not to forget that AI can be essentially a black or grey
             | box. You have some inputs and you have some outputs. Mostly
             | correct, but what if that fails catastrophically? At least
             | algorithms, in this case can be mostly walked through by
             | regular humans and errors possibly be noted. Unless the
             | complexity isn't idiotic in charge of profits.
        
           | Ekaros wrote:
           | Mostly they are there as sanity check. Just collect the
           | numbers and input in the system. Humans really can't be
           | trusted, especially with money. So someone in the loop have
           | to check can the information provided be trusted.
        
           | Brian_K_White wrote:
           | I think they mean algorithmic as in, simpler and
           | deterministic and auditable plain if/then/math algorithm, vs
           | black box magic AI.
           | 
           | Even if an AI can produce seemingly the same results as a
           | human, it should be out of the question anyway to let an
           | inscrutable black box make decisions over people's lives.
           | Because at least with a human you (their boss, or a judge,
           | etc) can ask them "Why did you decide that?" and they can
           | tell you. A racist or mysoginist or religious human can be
           | identified and fired or corrected etc. How do you judge if an
           | AI is giving inhumane decisions?
           | 
           | The decisions themselves can't really be judged, only the
           | process that generated them, and you can't see that process
           | in an AI.
           | 
           | If someone doesn't get a loan, and someone else does, you
           | can't tell that wasn't right just from the final result.
           | 
           | Even if the results "look" wrong, like only 30% of black
           | people get the loan while they made up 40% of applicants,
           | even that could possibly be exactly correct, but you can't
           | know if you can't see the process.
           | 
           | But a human can be asked, and simple algorithm code can be
           | read.
           | 
           | Probably these days the human has so little discretion anyway
           | that the corporate policy is the algorithm and the human is
           | pointless anyway except as a sham human-looking interface to
           | appease customers. It helps sales to have a human, but the
           | human in fact wields none of the human power that the
           | customer wants a human for.
        
           | cosmodisk wrote:
           | Those days when you dress up, go to your local bank and the
           | banker makes a decision based on their 'knowledge' about you,
           | are long long gone. Loan applications are standardised and
           | things like credit scores play big role. Things are probably
           | a little bit different when we are talking 7-8 digit loans.
        
           | notahacker wrote:
           | The absence of human picking up obvious discrepancies the
           | model isn't trained on or doesn't accept as inputs is an
           | order of magnitude or three less expensive than making more
           | bad loans (of the size/rate that aren't already determined by
           | a basic credit check). Also, checking the loan matches the
           | bank's credit criteria isn't the only task a bank employee
           | performs during the course of their employment, which likely
           | includes quite a few the AI is utterly terrible at, like
           | talking to people.
        
         | Ataraxiaist wrote:
         | Every bank is already using a data driven model for credit
         | decisions too. I am sure that is the major input for the human
         | decision already.
        
       | graycat wrote:
       | Some more details would be nice.
       | 
       | So a loan can be good or bad. The loan officer can rate it as
       | good or bad. And the software can rate it as good or bad.
       | 
       | To evaluate the situation, would like more than the "95%":
       | 
       | (1) Would like to see the arithmetic that yielded the "95%". (2)
       | Would like to know the rate (probability) of _false positives_ ,
       | when the software said the loan was good but it wasn't. (3) Would
       | like to know the rate (probability) of the _false negatives_ when
       | the software said the loan was bad but it was good.
       | 
       | And, really, when the software and the loan officer disagreed,
       | what were the _ratings_ of the applications and when was the
       | software correct and when, the officer correct.
       | 
       | Finally, what was the average cost per mistake for the false
       | positives and for the false negatives. E.g., a false negative
       | could cost the bank some business but a false positive could cost
       | them $millions.
        
       | epolanski wrote:
       | I don't think you need AI. Like in Italy the total of your loans
       | cannot exceed 1/3rd of your monthly salary, as simple as that.
        
         | kqr wrote:
         | Does this mean most Italians rent their homes for life and a
         | small fraction purchase their homes in cash?
        
           | epolanski wrote:
           | No, we have some of the highest home ownerships in the world.
           | 
           | 1/3rd of salary is more than enough to buy you a home. That's
           | enough to get a 200k loan for 30 years while making average
           | salary (1700 net euros).
        
             | kqr wrote:
             | Aha you mean the _interest_ cannot exceed 1 /3 of salary,
             | not the principal? That makes more sense.
        
               | epolanski wrote:
               | I'm not sure I expressed myself correctly: whatever you
               | make you can't have your loan payments exceed one third
               | of your monthly salary. So if you make 2000 euros, your
               | loans cannot exceed 666 EUR.
        
               | sokoloff wrote:
               | More likely to be based on the payment (principal plus
               | interest) than on the interest alone.
        
       | bencollier49 wrote:
       | Genuinely surprised that "bank managers" either exist or have any
       | say in loan decisions. In the UK it appears to be pretty much
       | entirely computerised, with a small amount of oversight from
       | teams of analysts if the computer decision is borderline.
       | Different elsewhere?
        
       | xiaodai wrote:
       | I reject 95% of loan application, so if u just predict reject
       | 100% of the time, then your accuracy is 95%. Just stupid shit.
        
       | fancyfredbot wrote:
       | If I run N different machine learning models over the same data,
       | and each has some random error in fitting the objective function,
       | then I pick the one which matches the validation data best, isn't
       | there a danger of picking the one which was "luckiest" with the
       | random errors? Presumably for large N that's a real problem? How
       | do people account for that?
        
         | mjburgess wrote:
         | https://en.wikipedia.org/wiki/Cross-validation_(statistics)
        
           | fancyfredbot wrote:
           | Cross validation doesn't solve that problem. As the Wikipedia
           | article says: "The variance of F* can be large.[26][27] For
           | this reason, if two statistical procedures are compared based
           | on the results of cross-validation, the procedure with the
           | better estimated performance may not actually be the better
           | of the two procedures (i.e. it may not have the better value
           | of EF). Some progress has been made on constructing
           | confidence intervals around cross-validation estimates,[26]
           | but this is considered a difficult problem. "
        
             | mjburgess wrote:
             | Well the historical data {(x, y)...} is assumed to be
             | distributed according to the true distribution, such that y
             | = t(x) where t is the true function which maps x to y. Of
             | course, in many situations, no such function exists (ie.,
             | there are genuinely ambigious xs, such that t(x) cannot
             | produce a single y -- consider an ambigous cat/dog
             | picture).
             | 
             | If we sweep models f1,...fn across the validation set ...
             | and choose max() of scores() of f1..fn on V, we get f*.
             | 
             | Now if your issue is that f* might be an "unlucky draw",
             | you're right. But there is no statistical way of fixing
             | this -- if we know (via experiment, etc.) what the true
             | distribution is, we can meaasure |f* - t| -- but if we knew
             | this, we wouldnt bother finding f*.
             | 
             | If you want a mechanism to mitigate these problems, there
             | is one main one: the scientific method. To test whether f*
             | poorly reflects t, go and do some experiemnts. If you
             | can't, then you wont know.
             | 
             | (Hence: there is no way of doing science via "mere
             | statistics". It is the experimental conditions constructed
             | by concept-laden, in-the-world, experimenters which are
             | able to obtain the sequence of datasets needed to give
             | confidence to any given model. ML is therefore not able to
             | know anything, its "conclusions" enterily derivative-of,
             | and limited-by, human experimentation. The intelligence
             | occurs in the experimental design, when that's done,
             | everything else is "stamp collecting").
        
       | ssivark wrote:
       | https://astralcodexten.substack.com/p/heuristics-that-almost...
        
         | nikanj wrote:
         | I was just coming here to post the same link. The 95% accuracy
         | should be compared to the general approval rate - does the
         | fancy AI beat a simple return true?
        
           | kqr wrote:
           | Yup. I always advocate that the first model one should build
           | is the one that constantly returns the most common answer.
           | 
           | That way, you can compare the more fancy stuff to something
           | to see whether you're really improving.
           | 
           | You also get to evaluate the economic gains of the more
           | sophisticated model against the development, maintenance, and
           | data costs of it, compared to the dumb one.
           | 
           | (Another good baseline is returning a random historic result
           | in proportion to how often it occurs. It sometimes helps
           | against exploit attempts at the expense of data.)
        
           | zwaps wrote:
           | The logistic regression would likely pick up on that if it
           | were a stratification issue.
        
       | lumost wrote:
       | I had an uncle who worked on a rural independent regional bank.
       | While this was a while ago, the bank could and would use a
       | variety of factors including references, propensity towards
       | substance issues and others to make a loan.
       | 
       | I wouldn't doubt that if you sat down, and created a data
       | set/data collection scheme to gather this data you could make an
       | algorithm to closely mirror the outcomes of a loan decision.
       | However as a human, the loan officer might simply add a new
       | criteria as desired.
        
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