Dec 19, 2012

The XL Files: Statisticians’ Impact, from Backyard to Bedroom?

Our new Contributing Editor, Xiao-Li Meng, used to be Chair of Harvard’s Department of Statistics, and has recently been appointed Dean of the Graduate School of Arts and Sciences at Harvard University. In this, his first column, he writes:

When Editors Dimitris Politis and Tati Howell invited me to be a Contributing Editor, it was well within the first 100 days of my wearing a new hat. I accepted the invitation immediately. Albeit still enjoying my honeymoon, I already had ample data to convince myself that the shortest article I could ever produce must be “Jokes for Deans” (not “Jokes of Deans”!). I therefore particularly appreciated the Editors’ enticing line, “We both like the way you write and appreciate your humor.”

Thank you, Dimitris and Tati! Fully appreciating the humor in this column will require years of statistical (and often Bayesian) training. Therefore, I now at least have a chance to offend someone without having to first remove my new hat!

All right, enough about my new hat. The “XL” label of this column is for Extra Laugh (inspired by the nickname Andrew Gelman gave me: Extra Large). But do take me seriously, as I intend to brag about our profession in a most serious way.

The most cited bragging line for statisticians must belong to Tukey: statisticians get to “play in everyone’s backyard.” Considering the ever-enhanced roles statisticians now take, I ventured in Meng (2009, American Statistician, 63, 202–210) to update the metaphor: “We are now being invited to everyone’s study or living room, and trusted with the task of being their offspring’s first quantitative nanny.”

But soon I realized that this metaphor still portrays statisticians as guests or temporary helpers, not fully reflecting that increasingly we are becoming serious partners, rather than mere consultants. Metaphorically, therefore, “bedroom” seems to be a better choice than “living room” to reflect how seriously we statisticians now are involved in substantive investigations. Indeed, at least to some, the bedroom is where intricacy, intimacy—even intimidation—take place. These associations are not inappropriate for our metaphorical purposes, considering the intricate problems we are often asked to handle, the intimate substantive knowledge we are somehow expected to have, and the mutual intimidation resulting from different jargons or perspectives in collaborations.

You may love or hate this metaphor, but, either way, I cannot take the (full) credit. The inspiration came from a story about my academic “grandfather,” William Cochran, as told by one of his daughters. Cochran was asked to examine a study on the effectiveness of natural birth control conducted in rural villages in a developing country. Due to resource and literacy constraints in these areas, the researcher gave each couple in the treatment group a “bead calendar” that was designed specifically for each woman. Beads were ordered by alternating bands of color, with red corresponding to the days to avoid mating, and green the “safe” days. The couples were instructed to count the beads and check the color before having intercourse. The study yielded results that were puzzling to the investigators, so Cochran was brought in. He quickly determined that the investigators had overlooked a simple fact. Those villages had no electricity: in darkness all colors looked green (or so the women were told by their husbands…)

I have my own link between statistics and the bedroom. A couple of years ago a young fellow introduced himself with the best compliment of my life: “Your article saved my marriage.”

It turned out that he was referring to the aforementioned 2009 article, which included a “parking dilemma” for teaching the trade-off between efficient and robust strategies. The parking garage I use has seven floors, and there are always spaces available on the highest floor. Parking on the lowest available floor is efficient, if I can remember which floor when I return late in the evening. Otherwise the robust strategy of always parking on the seventh floor is preferred, because it saves me walking up and down the stairs in the wee hours. Apparently, this young fellow and his wife were frustrated by a similar parking issue for their shared car, often not remembering/knowing where it was parked, but blaming each other. As the frustration escalated from parking lot to bedroom, my young fan was delighted to discover the simple solution offered in my article: always park in that seemingly least convenient spot.

Future XL Files will provide similar stories to lighten up your days. Drawing upon my experiences and observations, I plan to tell stories about statisticians in countless roles: mentor, researcher, educator, editor, writer, leader, speaker, negotiator, consultant, world traveler, philosopher, psychologist, historian, police officer, entertainer, meeting organizer, even angler and wine connoisseur. But if nothing lights you up, and you prefer to use the XL Files to put you to sleep, I’ll still be perfectly happy, because they’ll be in your bedroom!

Photo: Harvard University


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