OR history and traditions

The INFORMS History & Traditions Committee, added six new videos representing interviews of luminaries in the field of Operations Research and Management Science.  All of these interviews were conducted at the recent INFORMS conference in Nashville, TN, in November. Thank you to the committee and Irv Lustig for this great resource. The committee website has more resources.


Algorithms to live by

Algorithms to Live By: the Computer Science of Human Decisions by Brian Christian and Tom Griffiths is a nice book about how to live an efficient life. The authors interviewed me and included some of our conversations in the book. Below I include a snippet from the book summarizing how I once used the Secretary Problem to accept and reject bids when selling my house. It was ultimately successful and also pretty stressful. I blogged about it here. Other excerpts are about my research in emergency response and how I use the critical path method to get my three daughters to school on time every morning.

algorithms_to_live_by

 

Algorithms to live by on Punk Rock OR:


what Punk Rock #ORMS is reading

  1. Science: Beyond prediction: using big data for policy problems
  2. Harvard Business Review: the best ways your organization can support working parents (and work-life balance, in general). “Before launching any support programs for working parents, gather the relevant data: Where do parents sit within the organization? What are their attrition patterns? What information can you gather from annual performance reviews?”
  3. Thoughts on statistical consulting: the why, the how, and the difficulties
  4. To live your best life, do mathematics: how math promotes human flourishing
  5. A consideration of design as a form of participation in complex adaptive systems
  6. Why football teams should go for a 2-point conversion when trailing by 4 at the end of a game
  7. The meaning of spurious correlations
  8. Spurious correlations, visualized. My favorite is below 🙂
Cheese and civil engineering

Cheese and civil engineering


reminder: wicked problems are really, really hard to solve

My interest in public sector operations research has led me to appreciate so-called “wicked problems” (as opposed to “tame” problems). Wicked problems often reflect the soft side of operations research and are why some models are so complex. Due to the social component of the problem, there are many stakeholders with contradictory needs. A problem that is wicked quickly unravels due to the connections it has to other issues that are also social, and so on. Russell Ackoff summed this up nicely:

“Every problem interacts with other problems and is therefore part of a set of interrelated problems, a system of problems…. I choose to call such a system a mess.”

Here are a few slides on wicked problems from my Public Sector OR course:

It’s worth talking about wicked problems because I would argue that the Trump administration is not handling wicked problems well. Instead, Trump offered quick fixes to wicked problems on the campaign trail. That is not unusual, many politicians often do this before an election. I’m more concerned that the new administration is not willing to tackle wicked problems in all their complexity post-inauguration. Healthcare and immigration are wicked problems that cannot be “solved” by a quick fix! The implementation of the immigration plan was not planned, and unfortunately, several people have died as a result. Rushing through a wicked problem, especially when there are risks to life and limb, can be deadly.

The Republicans involved in the healthcare dialog seem to be acknowledging wickedness. That is promising.

I recommend C. West Churchman’s guest editorial in Management Science in 1967, where the term “wicked problems” was coined [pdf: Wicked Problems Churchman 1967] and this nice article on “wicked” problems by John Mingers in OR/MS Today.

Related reading:

 

 


what the birthday problem can teach us about when to have a baby

Carl Bialik at FiveThirtyEight recently posted a chart that summarizes when babies are born, which reflects attitudes and practices about scheduling inductions and C-sections. The chart shows that people are superstitious and have fewer babies on the 13th of each month, particularly on a Friday the 13th. I am not superstitious. My birthday is also on a 13th, although I was born on a Thursday. My mom had no choice in the matter because she went into labor naturally. But I’m confident she would not have shied away from the 13th.

This chart has implications for The Birthday Problem:

Given a group of n people, what is the probability that someone shares a birthday?

The canonical problem assumes that people are equally likely to be born on any day. If some days are more likely than others, then a match is even more likely. I simulated the birthday problem with a “mating season” here.

The data can be used to identify when hospitals have room shortages and when to have extra staff on hand. When I saw Bialik’s paper, I couldn’t help but think that the 13th of the month might be the ideal time to have a baby. Or the 15th. Or January 3. Or July 4.

We live in a world of limited resources, where we run some risk of not having enough of what we want. The above chart suggests that risk is not evenly distributed to all births. Having a baby on the 13th means that there is always a delivery room ready. If the hospital only has one bath for water births, you may have less competition for it. Or not. Having a baby on the 15th means that women who had babies on the 11th and 12th were discharged, leaving plenty of rooms in the maternity ward for mom and baby to recover.

When I had my third daughter, the hospital was out of rooms in the maternity ward. Only one woman was discharged, which meant that only one mother could be admitted. I was selected for the room because my daughter was born at home in a precipitous labor and accidental home birth. The staff felt that since I did not use a delivery room, I should get the room in the maternity ward. I was grateful.

This is not uncommon. You will always get a room, but you might have to wait in an uncomfortable place, such as a delivery room or elsewhere. I stayed by myself in the delivery room for hours after my second daughter was born instead of recovering in the maternity ward. It was stressful because I could not see my daughter for a long stretch of time, because security dictated that babies in the maternity ward could not leave. I was eventually taken to the maternity ward, where I discovered that my daughter was doing just fine and sleeping peacefully.

Mothers will always get a room somewhere eventually. Most women stay one to four nights in the hospital, depending on the details of the birth and their preferences about staying at the hospital if things are going fine. A hospital can be less busy for one to four days after a lull in births on the 13th of the month. I dealt with a hospital shortage after 2 of my 3 daughters’ births. None of their births were ideally timed according to my reasoning above. And none of their births were poorly timed on a busy day (see the heat map below)

So far I’ve talked about room shortage. Rooms are one type of limited resource. Staff are another. Staffing can be changed in response to trends in births, but hospital rooms cannot since there are only so many rooms in the maternity ward. Still, extra staff can make things happen to make the hospital run smoother when it’s busy. Discharges can be processed faster, for example, which can address a shortage of rooms.

I love talking about my daughters and analytics 🙂 Anyway, here is a heat map of birthdays.

A heat map of likely birth dates

For more reading:

 

 


My teaching journey: there and back again

Today I gave the keynote talk for the spring New Educator’s Workshop for teaching assistants at UW-Madison. I’m posting my slides here. My talk was entitled, “My teaching journey: there and back again.”

Abstract. I will talk about my journey from a painfully shy TA to a professor who is comfortable in the classroom and when talking to the media about research on the evening news. I will talk about strategies I used to be effective in the classroom given my strengths (and weaknesses).  Topics include time management, active learning techniques, easy ways to teach with technology, tips for managing student expectations, and things I wish I knew when I was starting to teach.

 

Blog posts that inspired my presentation:

 


Hidden Figures: my review (with a few spoilers)

“Every time we get a chance to get ahead they move the finish line. Every time.” Mary Jackson’s complaint about finding out that she needs to get a certification at an unsegregated men’s school before she can apply to engineering school summarizes the main theme of the movie. Hidden Figures follows Katherine Goble Johnson, Dorothy Vaughn, and Mary Jackson—human “computers” who worked in an all African American women’s division at the NASA Langley campus—and their trials and triumphs during the space race in the early 1960s. Intellect and ability may be color blind but opportunity was not. These capable women were used as temps, who temporarily joined teams at NASA to work on space projects based on whoever had an immediate need for a number cruncher. The opportunity to do anything beyond that (and get paid accordingly for it) was not available. The movie is based on the book by Margot Lee Shetterly and adapted by Ted Melfi (the director) and Allison Schroeder.

First of all, I really enjoyed this movie. It’s fun and memorable–parts of this movie will stick with me for a long time. I credit Octavia Spencer in particular for bringing her infectious humorous warmth to the film as Dorothy and to Ted Melfi for ensuring the movie felt authentic, both historically and on a personal level. The main characters do not feel like cardboard cutouts of real people. There is even discussion of math in the film. Melfi studied the math in depth before writing key scenes to make sure he could explain it to a lay audience. His hard work pays off. A high point of the movie involves a discussion of elliptical orbits and Euler’s method. The historically accurate details in the film brought authenticity to the movie. I knew some things were true before fact checking later. An IBM mainframe is delivered and cannot fit through the door. John Glenn tells NASA managers to “get the girl to run the numbers” before a final check before his historic Mercury 7 flight. The “girl” is Katherine Goble Johnson who saves the day with math.

The movie also succeeds because it makes the obstacles the women faced feel real and difficult to overcome. There were many obstacles to their success. This was the era of segregation, which meant separate bathrooms, drinking fountains, coffee pots, and sections in the library. There was only one women’s “colored” bathroom on the enormous NASA Langley campus. The human computers were being replaced with an IBM mainframe. Checking out a book on FORTRAN to program the mainframe at the public library was an ordeal because FORTRAN books were not in the colored section of the library.

While the movie follows a familiar formula, it feels fresh. Through Melfi’s steady direction, Hidden Figures clearly conveys that the seemingly small issue of the African American women not having a nearby bathroom is in fact a huge obstacle. Several scenes follow Katherine scurrying to and from the bathroom across the NASA campus (half a mile each way) for bathroom breaks in a skirt and high heels, the required dress code at the time. Each time, the plot movies forward in key ways. Katherine makes important contributions to the project, yet her name cannot go on the report since computers cannot author reports. Engineers can only author reports, so a white male engineer gets credit for Katherine’s work and Katherine is for the moment written out of history. Again, Melfi’s direction communicates these ideas visually. Throughout the movie, we understand that the myriad of small institutional barriers to inclusion and equal opportunity were like a ton of feathers that impeded all but the brightest stars from achieving what what anyone should be entitled to have. We still have institutional barriers today. Melfi doesn’t tell this to the audience, but instead lets them connect the dots on their own.

Most of the movie follows Katherine, Mary, and Dorothy at work, but they each have key scenes outside of work with their families. Early in the movie, we only know the main characters as African American mathematicians. Only later we learn that they have families. Katherine goes home and we discover that she is a widow and single mom to three daughters. This scene was my favorite. Katherine returns to her daughters after a long day of work. Her three daughters are fighting as they go to bed and irritated that their mother has to work. She does not apologize for working, and instead calmly gets her daughters to stop fighting and puts them to bed. She is both a good mother and mathematician. The director Ted Melfi got this right. Katherine eventually remarries in the film. From the moment she meets her future husband (Jim Johnson), he understands that she and her children are a package deal and the children are at the center of their relationship. All three women are working mothers pass on their values on to their children in a world where the rules are not fair. Dorothy and Mary tell their young children about injustices. Mary and her husband do not have the same temperament, but her husband supports her working toward an engineering degree. Later Mary becomes the first black women engineer to work at NASA.

This movie is not completely original but it was nearly perfectly executed. This movie will stick with me for a long time, and I’m anxious to see it again, this time with my daughters. I highly recommend it.

What did you think of Hidden Figures?

For more reading and listening: