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September 2010

Back from Penn State

I got back from Penn State today - I presented the work I have done with my doctoral student Ruken Duzgun in the seminar series of the Department of Industrial and Manufacturing Engineering. I have taken part in PSU's seminars several times over the past few years and always enjoy heading out west to catch up with my IE colleagues and their students (I schedule my talks to stay away from State College during the winter months, which might explain why I enjoy the scenic drive so much.) I got out before the influx of football fans, though; Penn State will be playing Temple tomorrow.

The faculty member who teaches a course similar to Lehigh's IE316 (my course on modeling real-life operations research problems and solving them on the computer) mentioned he uses LINGO (mostly) and GAMS (a little) in his course. In contrast, I focus on AMPL; I also like using Excel Solver to demonstrate Solver's limitations, and because Excel Solver is the only software taught in business schools. (The newly hired IE graduates will often report to MBAs, so it is important both groups "talk the same language".)

Unfortunately, LINGO is not free, and requires a license past the 60-day trial period. My PSU colleague requires a textbook that includes LINGO in a CD-Rom, thus making it easier to adopt the software. GAMS and AMPL can be downloaded for free with no time restriction; problems too large for these simple versions can be solved using the NEOS server. (There are some inconveniences, such as the fact that the NEOS server does not allow for .run files in AMPL; companies will certainly prefer buying their own licenses to take advantage of the software's full capabilities.)

As for the GAMS vs AMPL debate, that colleague's opinion was that GAMS is more used in industry than AMPL - maybe because no one wants to be seen using AMPL's DOS interface, which shows its age. But I find AMPL a lot easier to learn than GAMS; this helps students with limited training in optimization software catch up quickly. The most annoying feature of GAMS, I think, is that it only uses sets rather than numbers to describe the indices of decision variables. (AMPL allows both options.) This means that in GAMS, you can't simply go from time (index) t to time t+1, or sum from time 1 to time t, as t is not viewed as a number but as a character. The trick is to count the elements in the set of time periods and tell GAMS to use the one ranked immediately after t (to reach t+1), or sum all the elements whose rank is t or lower (for the sum).

In addition, the fact that the objective must be defined as equal to a dummy decision variable is somewhat irritating. But a great advantage of GAMS is that it imports data from, and exports it to, Excel spreadsheets with remarkable ease. So I will probably have a lecture toward the end of the semester where students learn to translate the problems they have written in AMPL into GAMS. This way they will not have to bother with the modeling part (which they will have already seen), but will enter the workforce with some knowledge of both types of software. This should make for an interesting week in December after our last quiz.

One thing I had not noticed until this trip to PSU is the aggressive branding of the State College area as "Happy Valley". I couldn't decide if it was a pure marketing gimmick, a hint at Penn State's status as #1 party school in America (downgraded to #3 by Princeton Review this year) - I guess you can say students tend to be happier when they party - or a subtle reminder that, as I was told, home values have held up despite the recent turmoil, showing that residents don't want to leave.

If State College markets itself as the "Happy Valley", maybe the Lehigh Valley should brand itself the "Lucky Valley" (my non-local readers, who represent most of my readership, should be reminded of the Sands Casino nearby to understand the pun). It sounds corny, but not much more than Bethlehem calling itself the Christmas City when it has nothing to do with the birth of little Jesus. (Click here for a list of cities named Bethlehem, including Bethlehem, GA, which is mentioned several times in Barbara Kingsolver's The Poisonwood Bible and is, in that respect, more famous than its PA counterpart. Maybe that will change once Bethlehem, PA has its very own novel.)

Penn State is a remarkable university with multiple facets: top party school and "Public Ivy" (top 15 public university, according to US News), "credited with having the second-largest impact on the state economy of any organization, generating an economic effect of over $17 billion on a budget of $2.5 billion" (source: Wikipedia.com), described as having "the largest dues-paying alumni association in the world" (ibid.), a strong Greek system, a famous dance marathon and a long list of notable alumni. While the IE major is only one of the many academic programs available in State College, it can't hurt that the department is ranked among the Top 5 in the country.


Research and Higher Ed

The Economist recently published a provocative column entitled: "Declining by degrees: will America's universities go the way of its car companies?" The column makes many interesting parallels between the two sectors, and provides numbers that give pause:

  • "Median household income has grown by a factor of 6.5 in the past 40 years, but the cost of attending a state college has increased by a factor of 15 for in-state students and 24 for out-of-state students."
  • "In 1961 full-time students in four-year colleges spent 24 hours a week studying; that has fallen to 14," 12 of which are taken by Prof Thiele's IE 316 assignments (just kidding).
  • "Only 40% of students graduate in four years."

The columnist speculates that "professors are not particularly interested in students’ welfare" because of misplaced incentives rewarding research rather than teaching (shockingly, "[t]his year 20 of Harvard’s 48 history professors will be on leave"), points at a worrisome trend in science and engineering where - according to the Kaufmann Foundation - productivity of R&D funding has flagged, and highlights increasing "administrative bloat" in universities. In addition, the author does not seem to believe that the situation can be changed since colleges tend to compete on academic reputation and amenities rather than quality of teaching. This certainly paints a bleak picture of US undergraduate education today.

Providing a different perspective, Prof Mike Trick from Carnegie-Mellon recently listed on his blog the 50 US institutions whose undergraduate students are most likely to earn a PhD within 9 years of their college graduation. (This list can be found in the study "Baccalaureate Origins of S&E Doctorate Recipients" by the National Science Foundation.) As Mike points out, the list is notable for the emphasis on universities classified as "research-very high" (RU/VH) institutions or "baccalaureate" (meaning that they do not have graduate programs) in the 2005 Carnegie classification.

The "research-high" (RU/H) institutions are remarkably absent from the rankings, except for the College of William & Mary and two Master's granting institutions. In addition, just about every single school in the list (with the exception of the College of William & Mary again, UC Berkeley, New Mexico Institute of Mining and Technology and the partial exception of Cornell) is private rather than public. Harvard itself is 11th on the list.

This raises fascinating questions regarding the effectiveness of undergraduate teaching at research-high private institutions, especially in terms of encouraging students to push the boundaries of knowledge and fostering a culture that supports this goal. How do colleges such as Harvey Mudd, Reed or Swarthmore, with no graduate research programs of their own, manage to interest so many undergraduates into cutting-edge research (after all, that is what getting a PhD is about), while PhD-granting universities with more moderate research activity do not, by far, engage their own undergraduates to the same extent?


Lehigh ISE graduate students continue to shine on national stage

This has been a great few years for my department of Industrial and Systems Engineering here at Lehigh, with former students Dr Ying Rong and Dr Jim Ostrowski receiving national recognition last year for their work:

  • Ying was a finalist in the 2009 MSOM Student paper competition for his paper entitled "Bullwhip and Reverse Bullwhip Effects under the Rationing Game" supervised by my colleague Prof Larry Snyder (MSOM is a society of INFORMS, the Institute for Operations Research and Management Science - MSOM stands for Manufacturing and Service Operations Management),
  • Jim received second prize in the George E Nicholson student paper competition (which is the general student paper competition run by INFORMS for papers in operations research and management sciences) for his paper entitled "Orbital branching", which was advised by my then colleague Prof Jeff Linderoth, now at Wisconsin-Madison.

I am happy to report that the department has received another finalist spot, this time through Ban Kawas PhD'10 in the 2010 Informs Financial Services Section paper competition, for her paper entitled "Short sales in Log-robust portfolio management", which I supervised. The winners will be announced at the annual meeting in November. Ban will start a postdoctoral fellowship at IBM Research Lab in Zurich in a few weeks.

It is very exciting to see the work of our graduate students receive such recognition in a wide array of operations-research-related areas, from supply chain management to portfolio management to pure optimization. We hope the trend will continue!


A New Type of Online Auctions: Swoopo

One of my former students (from many years ago - it is wonderful to see he remembers his IE professors, although his career took him in a very different direction!) recently drew my attention to an online auction site called Swoopo. The novelty of Swoopo, as described on its Wikipedia page, is that its users must first purchase the right to make bids, called Bid-credits, before they can actually place those bids; Wikipedia explains: "for the US version of the site, Bid-credits cost $0.60 a piece and are sold in lots (called BidPacks) of 40, 75, 150, 400 and 1000. Each credit is good for one bid. Standard auctions begin with an opening price of $0.12, every time someone bids the price increases by $0.12... The money collected by Swoopo consists of the cost of bids placed and the final auction amount."

Swoopo has received quite a bit of attention in the press, not always in the most flattering terms. A July 2009 article in the Washington Post stated it "might be the crack cocaine of auction sites... combin[ing] the addictiveness of auctions and the chance of lotteries into what may be the most devious way to separate folks from their money yet devised." This article provides the example of a MacBook Pro with suggested retail price of $1,799, which sold on the site for $35.86: "For each 'bid,' the price of the computer goes up by a penny, and Swoopo collects 60 cents. To get up to $35.86, it takes a stunning 3,585 bids [auction started at $0.01] -- and Swoopo gets its fee for each. That means that before selling this computer, Swoopo took in $2,151 in bidding fees." The winner of the MacBook Pro himself "bid more than 750 times, accumulating $469.80 in fees." (He/she still obtained the computer at a discount.) The Washington Post article is truly excellent in its analysis of the customer behaviors that Swoopo has built upon to become so successful; see for instance the discussion on sunk costs.

A related article is Sites ask users to spend to save, in the New York Times (August 2009). It provides examples similar to that of the MacBook Pro and mentions a change that Swoopo implemented in the summer of 2009, which is to let users who have not won an item apply the costs they incurred bidding toward the purchase of the same item directly from Swoopo. The New York Times states that "Swoopo's retail prices are marginally above those offered by sites like Amazon"; the article also briefly touches upon the issue of gambling vs auctioning. Although its business models makes it closer to an auction site than to an online gambling website, Swoopo has even retained a well-known gambling lawyer as part of its team, just in case. A law professor explains: "It turns out the idea of paying for bids does not seem to be specifically allowed by states, as it is in most of Europe. But it doesn’t seem to be explicitly prohibited either."


Math Moment

USA Today announced a few weeks ago that the College Board would stop "penalizing guesses" on AP tests. The formula used to compute scores had been: (number of correct answers) - (1/4)*(number of wrong answers), given that there were five possible answers for each question. I love the mathematical side of it. The idea behind the formula is that, if you have 100 questions and answer randomly each one, you have 1 chance out of 5 to find the correct answer although you do not understand the material. Counting only correct answers would yield an average score of 20, while in fact you really deserve 0. So your score is pulled back by 20 by dividing the total number of wrong answers (80) by 4, which is the number of wrong answers for each question.

Seen another way, your expected score for each question with 5 answers should be zero if you don't know the material, but the probability of guessing right is 1/5 and of guessing wrong is 4/5, so with w the weight for the number of wrong answers, you solve 0=(1/5)*1+(4/5)*(-w), which yields w=1/4.

Inside Higher Ed explains that the change in policy is due to the College Board's decision to redesign some of its AP courses, including the science ones. A draft of the proposed changes in the biology curriculum is available here (in pdf format); the goal is to increase depth of understanding by limiting the breadth of the content covered and using scientific topics drawn from cutting-edge research. The changes are classified into four areas: conceptual understanding, investigative skills, modern thinking in science and quantitative (computational) thinking. Specifically, "students will be encouraged to develop their ability to apply mathematics to wide sectors of biology so that they can better test hypotheses, model biological phenomena, interrogate complex data sets, and represent and interpret visualizations of relationships." I have never read the expression "interrogating data sets" before, but I love the idea. The ability to analyze data has certainly emerged as one of the key skills of scientists and engineers alike.

I couldn't figure out, though, why the change meant the end of the guessing penalty. Assuming multiple-answer questions are still offered (which is the only financially viable scheme to grade such a large number of exams in a small amount of time), students will always have the temptation to guess, so the only way the announcement makes sense will be if the deeper understanding they gain from the revised curriculum always allows them to eliminate some of the answers and make an educated (rather than uneducated) guess. It does seem a little premature to say that the changes will for sure lead to improvement in students' mastery of the concepts. One could argue that the whole concept of using tests with multiple-choice questions to assess deep understanding is flawed; I wrote about this here. But until computers can grade proofs correctly, those are the limits the College Board has to work with. 

The SAT, however, continues to penalize wrong answers.