Edouard Chazal

In Defense Of The Gaussian Copula

The Gaussian copula is not an economic model, but it has been similarly misused and is similarly demonised. In broad terms, the Gaussian copula is a formula to map the approximate correlation between two variables. In the financial world it was used to express the relationship between two assets in a simple form. This was foolish. Even the relationship between debt and equity changes with the market conditions. Often it has a negative correlation, but other times it can be positive.

That does not mean it was useless. The Gaussian copula provided a convienent way to describe a relationship that held under particular conditions. But it was fed data that reflected a period when housing prices were not correlated to the extent that they turned out to be when the housing bubble popped. You can have the most complicated and complete model in the world to explain asset correlation, but if you calibrate it assuming housing prices won’t fall on a national level, the model cannot hedge you against that happening.

→ The Economist

Your Life Is Tetris — Stop Playing It Like Chess

The decision to quit was liberating, terrifying, and confusing. Why did I feel so free when I had given up one of my first loves? But quitting felt good for the reason that starting to play chess felt right in the first place—it was entirely my choice to do so. And with that decision, my competitive, causal chess mindset began to weaken, and my perspective finally cleared.

Meanwhile, Tetris began to fill my gaming void. I play Tetris every day, and every day I pick up the game knowing that I will lose. How long will I play before I lose? How fast will the pieces go? How much will I score? Those are the metrics the game tracks. But I added a way to win—I win if I play Tetris every day.

→ Quartz

The Buddha Of Kabul

When I first came to Kabul, I had, like so many others, known it through war. Moments like these forced me to ask myself why it should come as a revelation that a 3,000-year-old city has layers that are diverse and different from its present. It says something about the way we perceive and talk about Kabul. Perhaps it is just human nature to ignore what is buried and only pay attention to what is apparent and overt. But occasionally, the city raises an aspect of its past almost as if to prove that it did exist, as a reminder of how much is lost, and how much remains within.

• • •

These links to the past are so fragile, made of clay and dust. So easy to break, so easy to return to the earth they came from. Yet these are also the objects that remind the forgetful world, and Afghans themselves, of what they used to be, of the confluence of ideas and civilizations that formed their khak, their ancestry. When I asked Zafar why he works so hard to excavate and preserve the material remains of Afghanistan’s history, he replied flippantly, “Because I am in love with Buddhism, and archaeology.” If so, it is a fraught romance, as the country’s past has been erased over years of war, and now, over an uncertain, uneven peace. Zafar has learned to be like the patient lover of a volatile partner. He cherishes what he has, without asking how long it will stay.

→ Guernica Magazine

Can An Artist Ever Really Own A Colour?

Invisible energy … Vantablack, which absorbs almost all light that hits it. Photograph: Surrey Nano Systems

Long before Klein created IKB, painters and their patrons paid through the nose for the rarest of pigments, lapis lazuli. This mineral that creates the colour ultramarine has only ever been found in Afghanistan. In the middle ages, it was mined there and traded at enormous prices to create European images of the blue heavens. Gold leaf was then daubed on it to make stars.

Colour is magical, colour is divine – you can’t blame Anish Kapoor or his critics for going mad for Vantablack.

→ The Guardian

Leaving Europe Would Be A Leap Into The Light

Michael Gove :

The EU is an institution rooted in the past and is proving incapable of reforming to meet the big technological, demographic and economic challenges of our time. It was developed in the 1950s and 1960s and like other institutions which seemed modern then, from tower blocks to telexes, it is now hopelessly out of date. The EU tries to standardise and regulate rather than encourage diversity and innovation. It is an analogue union in a digital age.

→ The Times of London