Tuesday, June 30, 2009

Data-Mining 1.6 Million Putts for Irrationality

A recent study by Professors Devin Pope and Maurice Schweitzer of the University of Pennsylvania concluded that professional golfers are more likely to make the same putt if it is for par than for birdie. (Par is the expected score for a hole; anything worse is bad. Birdie is one stroke better than par, which is good.)

Duh. Par putts are usually shorter than birdie putts because the player has used an extra shot to get the ball closer to the hole.

The study only compared par and birdie putts of the same distance. It used a database of 1.6 million putts, accurate to the inch, from Professional Golf Association tournaments between 2004 and 2008.

What about position on the green? Greens have lots of different slopes, so the same-distance putt can be easier or harder depending on where it is. If you took an extra shot to reach your position on the green, as the par-putter did compared to the birdie-putter, you should have been able to pick a more favorable spot.

The authors accounted for that. Position on the green indeed led to variance of putting performance overall but did not have a significant effect on birdie versus par putting performance.

Well, par putts are often second putts, after a player has missed a birdie putt. That means the player has already seen the green’s speed and angle from the first putt. Even if the distance is the same between a birdie and par putt, this extra learning will help sink more par putts.

It does, but it only accounts for 20% to 30% of the difference. The authors controlled for that effect, as well as a player’s learning from watching other players’ putts on the same green.

Hmmmm, sounds like the authors were thorough.

We’ve only covered some of the effects the authors tested and controlled for.

But how widely does the finding hold?

The authors tracked 188 professional golfers. All of them were better at par putts compared to equivalent birdie putts.

How much better?

Other than for the shortest putts, which were rarely missed, the difference varied between two and four percentage points, depending on distance. The best players tended to have less difference, although it was still statistically significant.

And why does this matter?

First, it’s a great example of a rigorous data analysis, the kind that can handle challenges like those above with aplomb.

Second, the conclusions are not just about golf. They have wider applicability to the debate about whether people are predictably irrational. In the golfers’ case, they treated the exact same putt differently, even though it was worth one stroke either way. The authors hypothesized that the golfers were exhibiting a flavor of irrationality known as loss aversion: The players perceived a missed par putt as a loss because par is expected, whereas a missed birdie putt was more like an unrealized gain. Standard economics suggests that people do not act differently based on such perceptions; the study suggests they do, even if they are highly skilled professionals.

Where can I read more?

The academic paper is available, but it’s not exactly a beach read. For a more approachable summary, see this New York Times article.

Sunday, June 14, 2009

New York City’s High Line

In 1980, the trains stopped running along the High Line, a mile-and-a-half of elevated railway in New York City’s Meatpacking district. By 2000, the abandoned rail line’s topside had become a scruffy greenbelt, unseen by those on the city streets below. Photographer Joel Sternfeld documented the High Line then with photos like this.

Around that time, some citizens had an idea: Let’s save the structure from demolition and make it a park. Such things are easier said than done, but they did it. The first phase of High Line park opened to the public on June 9, 2009.

I happened to be in New York this weekend, so I walked the High Line. Although it is now a public space, the High Line still evokes its former self. At many points, stretches of track remain, plants pushing up between the railroad ties.

Below is a photo from Ed Yourdon that gives the feel. Keep in mind, what you’re seeing is three stories above street level.

Congratulations to all those involved with the project. It adds a new dimension to the term urban renewal.

[For further perspective on the High Line’s architecture and landscape design, including a slideshow and video, see Nicolai Ouroussoff’s review in The New York Times.]

Wednesday, June 10, 2009


Below is the “GE basic floodlight 45.” I direct your attention to little “TM” next to the word “basic.” The “TM” is an attempt to assert a trademark on the word “basic.”

From Wikipedia’s Trademark page:

A trademark or trade mark is a distinctive sign or indicator used by an individual, business organization, or other legal entity to identify that the products or services to consumers with which the trademark appears originate from a unique source, and to distinguish its products or services from those of other entities.

Even within the context of floodlights as a product category, it’s unclear how the word “basic” provides any uniqueness or distinction. So how can that “TM” be there?

“TM” indicates an unregistered trademark, which is just a unilateral assertion of trademark. For example, whoever at GE decided that “basic” was worthy of a “TM” did not need to ask a government agency for permission. With an unregistered trademark, the classic Nike slogan applies: you can “just do it.”

But wait, that Nike slogan is a registered trademark, denoted by an R inside a circle. In the United States, it means the U.S. Patent and Trademark Office found the mark to meet the USPTO’s criteria for distinctiveness and such. With this government endorsement, a registered trademark provides a far firmer legal basis for defending a mark.

So the next time you see a dubious “TM,” remember that “TM” is more bark than bite.