Luca Dellanna Profile picture
Antifragile organizations & operational excellence • Complex systems researcher • • Disclaimer:
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23 Nov

Probably, 20% of the tweets you read deliver 80% of the value of using Twitter.

You'd be a fool not to prioritize your feed.
Here's how I do it.

(thread, 1/5)
2/ First of all, I set up a Twitter List of the 20 accounts from which I get the most value, and I pin it to my Twitter app.

This is my default feed. Because there are few accounts, I can find the time to read all their tweets even on busy days.

For the rest…
3/ For the rest, I use an app called Mailbrew

I created a digest w/ "news" that gets delivered every morning in my inbox. Because it only shows the top 3 tweets by account, it ensures I only read the best… (affiliate, but I use it daily since 2 months)
Read 10 tweets
17 Nov

1/ The worst possible outcome is forgiving student debt without changing the structural problems that led to this situation.

This would only make tuitions higher & reduce access to higher education, as described below.

2/ As a general principle, solving the symptom of a problem without solving the underlying causes is a terrible idea. It removes the urgency to solve the problem once and for all, making it grow larger.
3/ One question worth asking is, why is student debt not a problem in Europe?

The naive answer: government subsidies to students.

The real answer: contained costs.

The total operational costs for my ex-university in 2018 were "just" $7.8k / student / year.
Read 11 tweets
16 Nov

Italy assigned to each region a COVID risk level based on a complex model with 21 parameters.

Many experts claimed that the more parameters, the more precise the model.

Is it true, though?

2/ In most real-world cases, more parameters lead to worse predictions.

See the example below (from my ImageImageImage
3/ If we order the 21 parameters by descending predictive power, and apply it to the data used to build the model, we discover that:
- The first parameter alone predicts the outcome of many regions.
- The last parameter, at most, helps predicting the outcome of a single region.
Read 6 tweets
12 Nov
(and announcing my new newsletter 🎉)

Too much noise, too little content we actually use.

Take your favorite newsletter. Can you remember the contents of the edition-before-the-last-one?

Me neither. But I have a solution

(thread, 1/N)
2/ Today, I launch the RoamLetter.

A newsletter whose content directly integrates into your note-taking system.

A newsletter whose editions AUTOMATICALLY link with each other *and with your notes* 👏

A newsletter with built-in spaced repetition.

A timeless newsletter.
3/ If you are a Roam user, you'll enjoy how the topics of one edition of my newsletter automatically link with your body of knowledge, and the other way around.

If you are not a Roam user, no worries. You can still use all the other features of my newsletter (pics below)
Read 13 tweets
4 Nov

3 days ago, I published the first @RoamResearch book ever (

Once you try this format, you won't come back.

Here are 5 of its features (thread, 1/6)
2/ The first feature of Roam books, or rBooks for short, is that they allow for non-linear exploration.

Their pages are like Wikipedia pages – they contain links for optional deeper exploration.

Moreover, at the bottom of each page, there is an automatic list of references.
3/ Roam books are still books – they still have a table of content that guides you through your journey of discovery.

However, you can stray off the path or take shortcuts as you please.
Read 12 tweets
2 Nov

As a first effect, the virus bounces on the fibers. That's enough to decrease the distance at which it "jumps out". It might even get some of the particles to stuck to the fibers.

(thread, 1/N)
2/ Second, N95 masks also have electrostatic charges that capture particles even if they are smaller than the holes in the fabric.
3/ Third, masks would work even if the virus passed fully through.

They reduce the distance at which it travels after, say, a sneeze. It's as if they introduced additional distance between people.

Moreover, they work both on the way out and on the way in.
Read 7 tweets
1 Nov
More than 3 millions of Italians violated home quarantine (of those whose close contact tested positive or were waiting for test results),

according to the Italian Scientific Committee advising the government on COVID response.

Part of the problem is the slow testing.

6 million Italians should be in home quarantine, only a fraction of them because they tested positive. Most of them are there because tests are few and slow.
Another part of the problem is that enforcing the quarantine & working through the tests backlog is cheaper, easier, and more effective when there are few cases than when there are a lot,

But one would also need the will, capability, and wisdom to do so when it seems less urgent
Read 6 tweets
27 Oct

1/ They don't fully protect you from virus in the air.

Yes, but their point is to prevent as much virus as possible from getting in the air in the first place.

2/ There is this Randomized Control Trial I see posted on Twitter which allegedly shows that face masks do not work.

That trial shows that face masks do not protect doctors from patients *that do not wear face masks*.

Such studies do not demonstrate that face masks don't work.
3/ Paradoxically, the more you believe that someone wearing face masks is only partially protected, the more you should want everyone to wear them, so that there is less virus in the air.

That's how real herd immunity works.
Read 19 tweets
20 Oct
So, earlier today I posted a wrong tweet, which I then deleted. Thankfully, it only stayed on for a few minutes.

But I think it's important that I explain what I got wrong and why, for some could benefit too.

2/ I was commenting on this chart.

I correctly pointed out that the increase is relative. For example, it doesn't mean that more young people died than old.

However, I also wrongly added that the chart showed the increase in COVID risk for the young.

3/ I didn't consider that young adults tend to die of causes such as cancer that got impacted negatively by the lockdown (no cures)

The chart being about all-mortality, & the absolute number of young adults deaths being fairly low, the *direct* contribution of COVID might be low
Read 7 tweets
17 Oct
In yesterday's tweet, I was critical of scientific institutions endorsing specific parties.

Here is an example of why.

There is no such thing as "the scientific party" or "the anti-scientific one" – not if by science we intend real science, rather than a politicized consensus.
IMHO there's too much focus on who governs the political structure and too little attention to whether:
- The structure is good
- It provides good incentives
- It filters bad members
- The downside of bad decisions is capped
- It provides longevity to the common good or to itself
(I don't live in the US and this was not intended to be a reflection on the US; I merely stumbled on the quoted thread and it made me think. Many other countries will find that, if they remove the words and look at the actions, "scientific parties" aren't that scientific at all.)
Read 4 tweets
16 Oct
Why is it important to care about small HSE violations in manufacturing companies?
Shouldn't we only care about injuries & deaths?

Only if we want the company to fail and workers to die.

2/ Yesterday, I pointed out that a famous automotive company has a lot of OSHA violations. The most common response I got is that those relate to meaningless violations.

Perhaps. But only in a theoretical ideal world, meaningless violations are unrelated to incidents.
3/ In the real world, incidents *approximately* follow a pyramid as the below one (image from my book

The more "meaningless violations" a company has, the more a big incident is waiting to happen.
Read 7 tweets
3 Oct
I agree. Plenty of exceptions (that might be over-represented in my Twitter audience) but for most businesses, the below holds.

(Thread with motivations, 1/6)
2/ One reason is that hiring inside is Lindier than hiring remote – not from a historical perspective, but (see below) for the range of circumstances that must be true and must hold true over time for remote hiring to be effective vs in-house.

3/ (Yes, there are good examples of hiring remote, but I suspect there's a lot of survivorship bias in there. Also, it's possible that you hire a better-than-internal remote talent and still lose the long-term game due to externalities such as morale hits or cultural problems.)
Read 7 tweets
1 Oct

The reason is that we do not seek survival, but what feels like survival.

Any action that produces the same neurochemicals that we associate to pro-survival actions produces changes in our brain that make us desire it.

For example,

(thread, 1/N)
2/ For example, sugar gives us energy, and we need energy to survive.

When we eat sugar, our brain feels like we are increasing our chances of survival, REGARDLESS OF WHETHER IT IS THE CASE.

When we slowly kill ourselves through metabolic diseases, it still feels like survival.
3/ Our ancestors whose genes made them produce behavioral-reinforcing chemicals when they did something that increased their survival also tended to survive more.

Hence those genes spread. We ended up desiring repeating the actions that produced those neurochemicals.
Read 6 tweets
29 Sep
Natural selection is inevitable, but we can choose whether it acts on us (bad) or within us (good).

Up to a point, of course, but imagine a company:

If uncompetitive, the market's meritocracy bankrupts it

But the company can protect itself by letting meritocracy work inside it
2/ Natural Selection acts on any entity and within any population.

The monolithic only suffers from NS, whereas populations suffer but also benefit from it.

In fact, the monolithic is fragile whereas populations can be antifragile.

We can apply this insight by realizing that…
3/ if we consider ourselves a population (of habits & beliefs), we can let natural selection remove those that are bad for us, making us stronger. It acts within us

Instead if we consider ourselves a monolithic identity, we cannot grow. We become the victims of natural selection
Read 4 tweets
24 Sep

Often, the best approach is not A or B, but an alternation of A and B.

For example, action and reflection. Or study and application.

It’s not about balance, but about making hypotheses and verifying them.

Thread (1/N)
For example, the human cortex 🧠 is based on the principle of *alternating* two operations: expansion and compression of information.

Only one operation would not be able to achieve any meaningful result.

3/ Instead, the cortex alternates these two steps:
- It expands information across all possible hypotheses, relevant or irrelevant.
- It compresses information, by eliminating the hypotheses that are proved wrong by sensorial stimuli and/or experience.

This “brainstorm” is 💯
Read 11 tweets
23 Sep

The chart below shows the expected financial returns of a Russian Roulette gambler playing it multiple times.

There is no high-enough prize (nor low-enough cost) that make Russian Roulette worth it over time.

(thread, 1/N)
2/ Of course, there are reasons for which one would want to play Russian Roulette once.

But Russian Roulette cannot be a long-term strategy.
And it's not about cost-benefits.
3/ In a previous thread posted today, I compared GMOs to Russian Roulette.

Both come with a risk of ruin, and therefore none can become a strategy.
Read 7 tweets
15 Sep
"Ergodicity: Definition, Examples, And Implications, As Simple As Possible"

Announcing my next book, a project I've been working on recently.

2/ Ergodicity is one of the most important ideas in economics.

Sadly, most resources you can find online are directed to a readership of investors or require a high degree of mathematical understanding.

Hence, I decided to write the missing book.

3/ In this book, I talk about ergodicity in the simplest words possible.

I use practical examples most readers can relate to.

I give strategies to implement the learnings in daily life.
Read 7 tweets
15 Sep
Here is a practical example of why I keep repeating, “never use lagging indicators without pairing them to leading ones”
(Lagging indicators: measures of past results. Leading indicators: measures of the fundaments that determine future results.)
It’s not because of bad faith or opportunism (though sometimes they are contributions factors).

It’s more to answer questions such as, “are we gonna be badly hit by regression to the mean”?

Leading indicators tell us where the future mean / expectation is.
Read 4 tweets
14 Sep

Imagine that you want to have a simple way to evaluate whether an organization is likely to do well in the future or is at risk of implosion.

How to do that?

(thread, 1/13)
2/ The first consideration is that we cannot observe metrics that measure the past alone, such as revenue or past incidents. (These are called "lagging indicators".)

Many organization that collapsed did great until they suddenly didn't.

We must also include leading indicators.
3/ Lagging indicators tend to be "accounting metrics", whereas leading indicators tend to be behaviors (though exceptions exist).

This is because a success that isn't produced by sustainable behaviors is likely to be short-lived.
Read 13 tweets
11 Sep
“US sales of vinyl disks just surpassed CDs” (translation of the quoted headline).
I’d add that Lindy also applies to dimensions others than time, in a measure.

Over the dimension of “jobs”, vinyl players had 3 (playing music, pleasant piece of furniture, hobby) whereas CD players had 1 (playing music). Less Lindy across that dimension too.
As another example, a tech that is used in multiple countries across the world is Lindier than one used in only one, all other things equal.

That’s because the latter might work because of conditions specific to the one country adopting it; less likely for the former.
Read 4 tweets
5 Sep
An example of what I mean. Inclusive college admission looks inclusive only to a population who went to college.

Many of those who cannot go to college want to find good jobs without having to travel to a college the other side of the country leaving their parents alone.
Of course, inclusive college admission is better than non-inclusive one. But it’s still pretty non-inclusive, to everyone for whom college is not a viable option, and to all towns and families for whom having their young go away is not a viable option.
Decentralization would probably be more inclusive than any form of inclusive centralization.
Read 4 tweets