by Hari Balasubramanian

Optimization – the search for the best among many – is at the heart of the statistical and machine learning models that get used so extensively these days. Take the simple concept that underlies many of these models: fitting a mathematical curve to data points, better known as regression. In the simplest two-dimensional case, the curve is a line; in three dimensions, it is a plane, as seen in the figure. Among all possible planes – there are infinitely many of them, obtained by changing the angle and orientation: imagine rotating the plane every which way – we would like the one that passes ‘closest’ to as many of the data points (shown in red) as possible. Thus regression, often called the workhorse of machine learning, is really an optimization problem.

It turns out that optimization is fundamentally connected to even basic statistical quantities. Common statistics we we now reflexively use to summarize data – means, medians and percentiles – are themselves answers to certain optimization questions. We are not used to looking at them in this way.

Let’s take the average or sample mean, which, despite its obvious limitations, everyone turns to first. Suppose we have five numbers in a sample: 3,4,5,8 and 12. The sample mean is given by the straightforward calculation:

(3+4+5+8+12)/5 = 6.4

But there is another way to think of the sample mean: as the optimal answer to the following problem. We seek to find the x that minimizes (produces the lowest value of) the sum of the squared difference between x and each observation in the sample. Mathematically, we can write the function as:

(x-3)² + (x-4)² + (x-5)² + (x-8)² + (x-12)²

At what value of x does the function have its lowest value? In the figure below, the horizontal axis shows the values that x can take (I restricted myself to the range of the data points, 3 to 12). The vertical axis shows value of the sum of squares function corresponding to each value of x.

We see that the function follows a U-shape with the lowest/best value, x=6.4, occurring at the bottom of the U. Simple high school calculus – finding that point on the continuous curve at which the derivative is 0 – will yield the same answer. In fact, the formula for the mean, adding up all the sample values and dividing by the total number in the sample, can be derived using such calculus. Read more »

Nicholas Kahn and Richard Selesnick. Forgotten Crowns, 2013.

Archival pigment print.

More here and here.

by Emrys Westacott

Why do people care about sport? With hundreds of millions of human beings (myself included) obsessively following the world cup that is being played out in Russia, it’s a good time to reflect once again on this perennially interesting question.

Of course, it’s also true that hundreds of millions don’t give a damn about sport. I know the type: I’m closely related to a disproportionate number of them. To these people, the passion aroused by twenty-two men in shorts trying to force a ball between two sticks is a great mystery, and not something they find it easy to respect. In their view, even if they don’t say this out loud, getting all worked up over a soccer match is a) dumb, and b) good evidence that one needs to get a life. And they may be right. But that still leaves the phenomenon of sport-induced passion unexplained.

Since it is arguably the sporting event that occasions the most consuming passions, let’s focus on the world cup (although many of the points made will naturally apply to other sports also). And let’s distinguish, at the outset, between enjoyment and passion.

Why is soccer entertaining?

It isn’t so hard to understand why soccer provides enjoyable entertainment. First, and most obviously, a good match is dramatic; it has a compelling narrative. But unlike a play or a film, it is unscripted, which means the outcome is not determined in advance, and that makes a game genuinely exciting. Read more »

by Brooks Riley

by Holly Case and Lexi Lerner

What follows is part of a collaborative project between a historian and a student of medicine called “The Temperature of Our Time.” In forming diagnoses, historians and doctors gather what Carlo Ginzburg has called “small insights”—clues drawn from “concrete experience”—to expose the invisible: a forensic assessment of condition, the origins of an idiopathic illness, the trajectory of an idea through time. Taking the temperature of our time means reading vital signs and symptoms around a fixed theme or metaphor—in this case, the oxygen mask—to reveal how our everyday, recorded interactions can acquire extraordinary historical  momentum.

“Among the various exploits, vital or destructive, which oxygen can perform, we varnish makers are interested above all in its capacity to react with certain small molecules such as those of certain oils, and of creating links between them, transforming them into a compact and therefore solid network.”   —Primo Levi, The Periodic Table (1975)

“[A]t 40,000 ft, people have as little as 18 seconds of ‘useful consciousness’ time if they are starved of oxygen. […] [T]he risks of hypoxia–oxygen starvation–are all the greater as people may not realise they are suffering until they can no longer breathe and fall unconscious …”   —Lizzie Porter, “What happens when a plane loses cabin pressure?” The Telegraph (Feb. 3, 2016)

“‘Put on your own mask before helping someone else.’ […] I believe this is a metaphor for life.”  —Paul Dodd, “The Metaphor of the Airplane Oxygen Mask,”  Modern Enlightenment [blog] (May 16, 2015) 

***

“Before the oxygen apparatus was used I used to suffer a great deal from flying at high altitudes. […] I used to get this palpitation of the heart and headache when I would fly over 16,000 feet; I would also feel ‘rotten and done up,’ […]”     Air Service Medical, War Department, Air Service Division of Military Aeronautics (1919) Read more »

9-Lived Cat

.where are you

…on the willow-hung swing
…in a goldfield of grass
where
…in the hemlock
…straddling the branch just below the top
…hands sticky with sap
where, where 
…sitting on the well-house step
…with the lake at your back
…remembering a future
…of victory or collapse
where
…on the topside deck above the bridge
…holding the cable-rail fast
…exhilarated at how the bow’s pitch feels
…spearing a new wave’s gut
…as green water breaks over steel
…and you feel up your spine
…the meaning of
…………………….….….splash!
…among zucchini
…grubbing for ones green and fat
…or off in a high in a twelve-string cage
…hoping to harmonize with truth in that
where
…are you tumbling up a shaft
…like a 9-lived cat

Jim Culleny
6/18/18

by Michael Liss

Let’s talk about bullets and ballots.   

First, a thought experiment. Your son is about to become a father for the first time, and you want to get him something special.  You have great memories of taking him hunting when he was a boy. So you go to a local gun show, and, at a booth manned by an old friend, you see a real beauty. He’s about to ring you up when something flashes on his screen.

“I can’t sell this to you…it looks like you haven’t bought a gun in at least six years.” He calls over someone official-looking; a long discussion ensues, including a certain amount of hand-waving, but the result is the same. No sale. Several years ago, your State Legislature, concerned about people getting their permits in-state and then moving elsewhere, had sent out postcards to those permit-holders who hadn’t bought a gun in the previous two years to make sure they still resided in the state. You could have responded to the instructions on the postcard, or simply bought a new gun from a licensed dealer in the four years that followed. But you didn’t—in fact, you don’t even remember getting the postcard, much less hearing that not returning it could be a problem.

Tough luck, especially when Democrats took back both the State House and control of the State Legislature. The dealer explained to you that you hadn’t lost your Second Amendment rights—no one was going to touch the guns you already owned or stop you from carrying or hunting—but until you updated your paperwork, the State assumed you had moved and the dealer was prohibited from selling something new to you. He was incredibly apologetic; your boys had played Little League baseball together; he’d even worked for your Dad when he was in high school; so there was absolutely no doubt in his mind that you were who you said you were, and lived where you said you lived, but the law was the law.  On this one day, not forever, but this day, you couldn’t purchase that particular gun. He’d put it aside for you, and, as soon as you got off the “No Buy” list, you could have it. Read more »

by Richard Passov

Robert Gordon is the Stanley G. Harris Professor of Social Sciences at Northwestern University. In a well-received book, The Rise and Fall of American Growth, Gordon ‘…contributes to resolving one of the most fundamental questions about American economic history’ by providing ‘… a comprehensive and unified explanation of why productivity growth was so fast between 1920 and 1970 and so slow thereafter.’ 

The ability to control electricity so that it arrives in measured doses where and when needed combined with simple steps to improve public sanitation, such as running water, indoor toilets and the removal of the uncountable tons of horse manure that marked major cities before the advent of the internal combustion engine that spurred roads and transportation networks that enabled frozen food to be enjoyed from coast to coast, wrought a step change in living standards unlikely to be repeated.

Economists know the growth in Gross Domestic Product (GDP) in any period. And total hours worked and the change in capital. They apportion contributions from labor and capital to GDP based on the amounts of income they ascribe to labor and capital.  What remains – the residual that’s necessary to arrive at the total growth in GDP – is Total Factor Productivity (TFP). You can think of this as conflating, in the measured period, smarter workers working harder with more and better capital. Or as one equation with three unknowns.

Going into WWII, TFP was elevated: jobs were scarce and to remain in business, an enterprise had to be extremely productive. During WWII, as Gordon points out, Government built an enormous amount of plant and equipment that was retooled to meet the pent-up demands of a population starved for consumer goods.  So no great surprise that the US continued to benefit from surging TFP post WWII.

Since 1970, according to Gordon, TFP has been missing. I know where some of it can be found.

* * *

Recently, I spent a few hot days in Phoenix Arizona at the Bondurant School of driving.

On our first morning, three instructors perched on a table at the front of the class.  Will was the lead. For the next few days I’d hear his flat delivery coordinating track time over the radio. Tyler, boyish and rail-thin, was assigned  to Camaro drivers.  The third instructor approached my group. “Well,” he said, “you guys must be here for the Corvette class. I’ll be working with you. ” Read more »

Javier Perez. Carroña, 2011.

Installation.

More here, here, and here.

by Brooks Riley

by Maniza Naqvi

Give me a break I mutter. I text—and I text. Incessantly I text. Send money. Now. Send money. More money. You don’t reply. You will. It is Spring and I am young. Everyone around me on the beach is around my age or younger. We are young.

I offer: Let’s chat. Then I wait. Stretching out leisurely I see stretching before me powdery pristine white sand, waves gently furling and unfurling, nibbling at the beach as far as my eyes can see—a cloudless blue sky mirroring a gentle ocean to my right. A gentle ocean—its blue so blue against the sky and the white that I cannot even give it a name—this blue—this blue of abundance. This blue of calm and peace. This blue of happiness. This combination of blue and white—this perfect sweet air, a fresh ocean breeze. And I am high, feeling the buzz—of this intoxicating time. The beach vibrates—undulates and shivers—trembles with life, the shells, clams and crabs– alive. On the distance horizon over the ocean I can make out cargo ships, probably Chinese and Dutch and trawlers, probably Japanese, netting the big fish. Our fish. Read more »

by Dave Maier

I’ve always been a big fan of logic puzzles, especially Japanese ones (heyawake, nurikabe, gokigen naname, hashiwokakero), but I recently ran across another kind of puzzle which has been driving me crazy. So I thought I would share it with you, so maybe you also may be driven crazy. You’re welcome!

I do this puzzle (called “Guess” in this version) on my iPad, and I got it as part of large collection called Puzzles, which means that if you search for it on the App Store, you’ll get a bazillion hits and never find this particular one. Luckily (or not), Guess is easily available under another name, Mastermind, the name of the board game it’s based on. I don’t remember ever playing this game, but the only difference, I take it, is that when it’s played by two humans, one player chooses the tokens while the other guesses, and one scores better or worse based on how long it takes to get the answer (or fails to do so). Guess doesn’t give points, but one naturally tries in any case to solve the puzzle in as few steps as possible — which involves figuring things out rather than simply guessing randomly. Read more »

by Katrin Trüstedt

Political debates in Europe these days seem to have only one subject. At one point or another they all turn to the issue of migration, Islam, and a danger to “the West”, which are presented as essentially synonymous. Germany’s political future seems currently to hang in the balance over the so-called “migration master plan” by German secretary of the interior Horst Seehofer. The polemical campaign of the CSU to win back voters from right wing parties threatens to blow up the German government and thereby endangers the future of Europe. In a time when it is increasingly difficult to deny the immense scale of suffering both in the places from which a majority of the refugees escape to Europe, and in the border areas they find themselves in, the construct of a “Fortress Europe” is being strengthened not only by physical and political, but also by rhetorical barriers. Returning to stereotypes of foreign invasions overrunning a weakened West, mainstream debates are drawing on old images already used in anti-Semitic propaganda of the early 20^thcentury.

Michel Houellebecq’s novel Submission, which recently re-entered the German discourse in form of a movie adaptation, seems to offer the apt allegory for the current phantasma. Perhaps its biggest accomplishment lies in foregrounding the strong but mostly implicit connection of this type of xenophobia with issues of gender and sexuality. The weakened West is depicted here in terms of the decline of the male, bored, and sexually frustrated protagonist who shows uncanny features of an Incel, and to whom the Islamic Other taking over France seems to offer a model for a renewed masculinity putatively under attack in post-feminism Europe. Ultimately, the only solution for the protagonist is a submission to the spreading Islam in order to restore patriarchy and repair his unsettled and offended masculinity with the vision of underage virgins. In all its absurdity, the novel points to an implicit thread of the new right wing discourses presently targeting Islam as the privileged enemy: that of a threatened masculinity. Informed by images of young Islamic men overrunning a decadent West unable to protect itself, the European discourse on refugees is deeply gendered and sexualized. Read more »

“…shimmering through the leaves and out beyond the black lines
of her neighbors’ chimney pots were the stars, beacons whose light
left them long before there were eyes on this planet to receive it…”
…………………………………………….. — archeologist Jacquetta Hawkes

Tripping on Curbs

we who live in deep space and trip
on curbs looking up at stars bound in a mesh
of interstices of lightyears through which
seas of breath and blood pass,
in which muscles are bound by mystic ligaments
to armatures of bone . . .
we’re always mystified by what seems a
phenomenal disconnect,
mindsparks shine here and there,
filaments of personal matter,
electric turns of tissue and dreams,
tiny conscious blips to which
oldest light comes, goes, scatters
and everything is it.
so it may not matter
if shimmering it
will or will not
shatter
.

Jim Culleny
11/04/16

by Brooks Riley