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Probabilistic thinking can lead to improved decision-making (quantamagazine.org)
195 points by nature24 on March 3, 2018 | hide | past | favorite | 12 comments



Thinking is hard. That's why we must strive to avoid it at all costs. :)

Probabilistic thinking is useful to wrap one's head around.

Having worked with decision support for a decade, I've come to realize that probabilistic thinking may or may not be useful to work into organizational decision making regarding change.

It's still a thought experiment, but I'll put in a shameless plug for the first of a series of blog entries: https://blog.henrikscorner.net/2018/02/25/a-modest-proposal/

In case of concerns: The blog itself is unmonetized.


The thing is people need certainty. Imagine a guidance from Apple saying they would make $2 per share with 47% probability. Investors will freak out. Which is why most companies sandbag their results. I want to know if any orgs actually use probabilistic decision making in their day to day operations.


> Imagine a guidance from Apple saying they would make $2 per share with 47% probability. Investors will freak out.

if that's all it said, sure, because that sounds like apple just made some insanely high-variance bet. if instead apple provided some nice smooth probability distribution over possible earnings, folks would react much more reasonably.


Imagine a guidance from Apple saying they would make $2 per share with 47% probability. Investors will freak out.

So? People freak out all the time about things that are true. It doesn't change that it's true.


Strictly speaking, one may end up with a separate set projections for e.g. dividends. These may in a standardized way present ranges for each KPI with confidence intervals associated.

I'd rather invest if that type of data were included. :)

As this is a somewhat large topic, I'll elaborate further throughout the series of blog posts.


That is an excellent point!

That is the very reason I believe the current system should be augmented with a new first class financial statement, rather than replaced. This will give investors better information, and managers will gain better decision support.

Those who prefer the old way of doing things remain free to carry on as before. Those who embrace it may compete better.

Of course, the same mechanism may prove useful for governmental organizations.


I forgot to answer your question: "I want to know if any orgs actually use probabilistic decision making in their day to day operations."

The short answer is "yes!" The long answer is, well, rather lengthy.

Check out the fields of advanced analytics and BI.


One big problem with that is that the uncertainty in the variance is probably larger than the uncertainty in the mean.


There are much more useful real-world examples of applied probabilistic thinking in search and rescue.

In conditions where you don't have direct contact with the search subject (and, sometimes, even if you do), there are a ton of factors to account for when deciding where to deploy resources and which resources to deploy.

Most search managers rely on gut feelings and experience, and in many cases, that works okay. They're familiar with the "hot spots" in their area where subjects tend to get turned around or hurt (or turn up if they've got a mental disability).

But there are many many searches where those tools totally fail them, and in those cases, I've seen searches stumble pretty badly and a ton of resources just get totally wasted as the manager re-deploys resources to the same places over and over again, totally certain each time that the subject is there and just somehow got missed by previous teams.

My favorite search-related text so far is "Lost Person Behavior", an analysis of the behaviors of past search subjects. It's far from perfect -- in some cases, it's relying on very small amounts of data or on data that's relevant to a specific area only -- but it's all we've got at the moment, it's a step in the right direction, and it's been right for the most part, even when the search manager was wrong.

I've also developed a personal rule that "40% of the information we've got is wrong" going into a search. Bad information is the result of a lot of hands touching the info before we ever get it. Everyone tries to be helpful, and they suggest things that then become facts. These bits of misinformation can misdirect searches really badly, so it's good practice to review all of the information you've got right away, and try to identify the bits that are most likely to be incorrect.

In the first quarter of 2017, we had a plane go down in a neighboring county that didn't have the resources to manage the search, so we handled it. It turned into a major search spanning almost a week, with CalOES on-site, along with air national guard, civil air patrol, and a half-dozen other agencies, and hundreds of feet on the ground. Along about day 3, I decided to re-review the data; there was a flight track from radar just before the aircraft disappeared, there was an eyewitness account that heard a loud aircraft engine but couldn't see it because of heavy cloud cover, and there was an intermittent ELT signal. We had some information on the conditions at the time. The area around the ELT had been searched, and re-searched, and was about to be searched again. Given that info, what would you do as a search manager?

The eyewitness account was from about the right time of day, and the guy didn't seem over-helpful, so it was probably reliable but all it told us was that there might have been an aircraft in the area at the time.

I decided to dismiss the ELT entirely, and instead reviewed the terrain, compared it to the flight track, and talked to a pilot. We assumed the pilot was capable and that they had a technical issue with the aircraft; given that, the flight track suggested they attempted to turn back, and then changed their mind. There was a narrow mountain pass just ahead of the end of the flight track, and then a long valley that suddenly ended in mountains. And that's approximately where the plane was eventually found, many miles from the ELT reports.

I reasoned that once the ELT area had been searched, the probability of the aircraft being there dropped considerably, and therefore the ELT was misleading the search. So, where would we search if there was no ELT?

This has been a recurring pattern in a lot of searches over the last couple of years, and I hope someday a sea change happens in search management that incorporates more of this approach.


> (From the article) Our brains reason better with causes, rather than with numbers. In variation B, the idea that Ones are more prone to the disease is a cause we can latch on to, and it helps us discount the results of the ethnicity test as we should.

The fact that variations A and B both have the same answer means that the likelihood of Ones having the disease is irrelevant to the problem statement. It's really funny that "Ones are more prone to the disease" in variation B is supposed to help us intuit the correct conclusion when it's not actually relevant information.

Writing the math out shows that P(disease=True) does indeed drop out of the P(identity=Two | disease=True, ethnicity-test=Two) calculation.

Edit: Adjust quote formatting.


Rosencrantz and Guildenstern


[flagged]


Try reading more than the tagline. I am well aware that probabilistic thinking is a better method of decision making, but that knowledge just tells me my gut feeling is probably wrong when considering questions like the ones posed.




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