Author Topic: Predicting death  (Read 49 times)

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Offline kimmy

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Predicting death
« on: October 01, 2018, 12:48:45 am »
I found this interesting.   I confess that I started reading this article because I was interested in the kitty.  But it goes on from there.

A computer science grad student at Stanford set out to design an algorithm to predict when terminally ill patients were going to die. The idea was that this could make more efficient use of palliative care resources.  Providing palliative care too soon is wasteful, providing it too late is of no value. The idea was to identify patients who were likely to die within 3-12 months, to make best use of their remaining time as well as of palliative care resources.

He developed a neural network system and fed it data from 160,000 patients to "learn".  Then, he applied his algorithm to an additional 40,000 patients and found that his system was 90% accurate in picking a 3-12 month window when their deaths would occur.

The problem is that although the algorithm has learned to process the data quite accurately, trying to figure out what exactly it has learned from the data is quite difficult:

Quote
So what, exactly, did the algorithm “learn” about the process of dying? And what, in turn, can it teach oncologists? Here is the strange rub of such a deep learning system: It learns, but it cannot tell us why it has learned; it assigns probabilities, but it cannot easily express the reasoning behind the assignment. Like a child who learns to ride a bicycle by trial and error and, asked to articulate the rules that enable bicycle riding, simply shrugs her shoulders and sails away, the algorithm looks vacantly at us when we ask, “Why?” It is, like death, another black box.

 -k
Paris - London - New York - Kim City

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Offline TimG

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Re: Predicting death
« Reply #1 on: October 01, 2018, 01:59:41 am »
The problem is that although the algorithm has learned to process the data quite accurately, trying to figure out what exactly it has learned from the data is quite difficult:
How to design an AI system:

1) Create a computer model that replicates the brain's learning networks;
2) Feed it massive amounts of training data;
3) Cross your fingers and hope it learns something more useful than exploiting random correlations in the training data.

Look at the phenomena of a 'bellwether riding' in a election. Media love them but there is no rational reason why a single riding would 'predict' the outcome of a general election. It is just a spurious correlation that happens to be useful until it isn't. Yet an AI designed to 'predict' election outcomes would likely notice and use such spurious correlations which makes the fact that we can't know why an AI is accurate even more worrisome.


« Last Edit: October 01, 2018, 02:07:49 am by TimG »

Offline Michael Hardner

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Re: Predicting death
« Reply #2 on: October 01, 2018, 05:50:08 am »
I concur with TimG.  It could be next-level magic or it could be the computer version of the Farmer's Almanac.

Offline Michael Hardner

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Re: Predicting death
« Reply #3 on: October 01, 2018, 06:00:23 am »
I just did an online quiz and I have about 30 and a bit years left.  I'll take it !

guest18

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Re: Predicting death
« Reply #4 on: October 01, 2018, 06:10:47 am »
Damn. You waited too late to have kids.

Offline Michael Hardner

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Re: Predicting death
« Reply #5 on: October 01, 2018, 06:20:34 am »
Damn. You waited too late to have kids.

Gee, thanks Bubber...  :(  That didn't occur to me.

My grandfather was 56 when his son, my dad, was born.  They had 33 years together, and I have had 80 years with my dad.  I didn't marry until after 40, and my sweetie decided to go to university, then post-grad which took 6 years ... It is what it is. Treasure all of your time.

Offline kimmy

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Re: Predicting death
« Reply #6 on: October 01, 2018, 10:02:55 am »
Look at the phenomena of a 'bellwether riding' in a election. Media love them but there is no rational reason why a single riding would 'predict' the outcome of a general election. It is just a spurious correlation that happens to be useful until it isn't. Yet an AI designed to 'predict' election outcomes would likely notice and use such spurious correlations which makes the fact that we can't know why an AI is accurate even more worrisome.

I'm not sure that any correlations are spurious... just correlations that we don't understand yet. A  bellwether riding might be that because of a historically useful mix of party preferences plus a large enough number of swing voters that its results are a clue where swing voters elsewhere will park their ballots.   With the availability of scientific polling and large amounts of data we can go back and figure out why Flatbush Ontario seems to predict the winner, but the pattern is visible before we have the information to understand why.

 -k
Paris - London - New York - Kim City

Offline Michael Hardner

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Re: Predicting death
« Reply #7 on: November 10, 2018, 03:57:11 pm »

Offline TimG

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Re: Predicting death
« Reply #8 on: November 10, 2018, 04:27:35 pm »
I'm not sure that any correlations are spurious... just correlations that we don't understand yet.
Huh? Most correlations are spurious. It is well recognized problem in science: https://www.researchgate.net/publication/247629474_Spurious_Correlation_and_the_Fallacy_of_the_Ratio_Standard_Revisited

Unfortunately, some fields are better than others at guarding against conclusions based on spurious correlations.

Simple statistics says that if you look at 30 random data sets you will find at least two which are correlated (https://www.xkcd.com/882/). That is why data mining is where people use correlations in large datasets is a dubious field. Post-hoc rationalizations for why a correlation is not spurious are not good enough. If you are given any two random correlated datasets you could probably invent a pro-hoc explanation for the correlation because it is easy to do. That does not mean the post-hoc rationalizations deserved to be called a fact or truth. It takes controlled experiments to establish that a correlation is a real relationship.

This chart really illustrates how dangerous data mining is:
https://www.motherjones.com/kevin-drum/2018/11/chart-of-the-decade-why-you-shouldnt-trust-every-scientific-study-you-see/

It shows that before the academic bodies forced researchers to register a study before it started we saw that only positive correlations were published which would give people a false picture of the efficacy of treatments. After the discipline was imposed most studies showed no significant effects.

« Last Edit: November 10, 2018, 05:33:56 pm by TimG »