Monthly Archives: January 2009

weather forecasts and low temperatures

One of my pet peeves is a weather forecast that doesn’t contain the current temperature. It has been colder than usual for the past 3+ weeks, and almost every day, the morning temperature outside is 5-10 degrees below the low temperature in the forecast. As I am checking the weather on TV, for example, the current temperature will be 16 with a low of 23 (See the picture below for an example of this). They can’t add an if statement to update the high and low temperatures for the day? Seriously.

Example of a broken weather forecast that doesnt contain the current temperature

Example of a broken weather forecast that doesn't contain the current temperature

I ran in a race this weekend. The forecast predicted a low of 28 degrees outside. But I ran 15K in 19 degree weather. As I was running and trying to distract myself from the fact that I couldn’t feel my face, I speculated that some aspect of large-scale meteorology algorithms resulted in bad low temperature forecasts. After all, weather forecasts seem to do a pretty good job predicting hot temperatures.

Amazingly, there is evidence to suggest that what I have been observing is in fact true! This blog post from ForecastAdvisor provides data showing that weather forecasts get worse as the temperature deviates more from normal. The key figure is illustrated below. Most interesting is that there is a bias toward accuracy in predicting hotter temperatures–forecasts for colder-than-normal weather are worse than hotter-than-normal weather!

Forecasted temperature error

Forecasted temperature error

Meteorologists: please explain this phenomenon in more detail! Read an old post about OR models for meteorology.


a second-hand account of the inauguration

One of my students attended the inauguration and indicated that there were at least three logistical problems:

  1. The Metro was indeed a mess. Much of the problem, however, was due to the fact that there were not enough personnel there to help the out-of-towners navigate the Metro, so the confusion was worse than the crowds. I can believe this. All tickets are purchased by automated machines. The fare cost depends on where you are going (not a flat fare), and there is a discount 9am–3pm. Parking is paid by different automated machines and I still haven’t figured those out. Compounding the problem was the rumor that someone was hit by a train, which stressed an already stressed system. This rumor turned out to be true–a 68 year old woman was hit by a train and luckily survived. More than 1.5M rides were taken using the Metro on Monday.
  2. The second logistical nightmare was trying to get onto the lawn at the Mall. About 240K tickets were issued, and there were not enough personnel taking tickets and letting people onto the Mall. The line was very long and people became impatient after waiting for hours. Watch the video here.  The crowds got angry and surged forward, breaking through the barricade of armed security guards. More than 4000 people with tickets missed the inauguration.  (Side note:  I have noticed that there is almost always a bottleneck at admission for special events.  Understaffing admission seems to be a common oversight).
  3. Going to the bathroom was indeed a challenge. The wait to use a McDonald’s bathroom took an hour, but at least there was toilet paper.

I skipped the inauguration

I did not attend the inauguration mainly due to unpredictable travel times and child care issues. But I followed it via web stream and news sites and wanted to write an update about the crowd estimates and logistical issues that I wrote about last week.

The crowd estimates were predictably less than the prediction of about 2 million people. The Washington Post reported that the total crowd size was approximately 1.8 million (including people attending the parade) and 1 million people on the Mall. Expert Clark McPhail estimated the crowd size to be 1 million on the Mall. He said, “It was sparser than I thought… There were lots of open spaces.” The Numbers guy reports the estimates that many networks were using and how they got them.

It seems like there were enough bathrooms. There are some reports of long bathroom lines, but in the end, the wait seemed doable. I was unable to find any articles about a major bathroom problem or the lack of toilet paper. Hooray!

Miraculously, the traffic going to and from DC was reported to not be too bad.  All bridges connecting Virginia to DC were shut down before the Inauguration, so I expected the worst.  It sounds like heavy congestion was limited to Metro stations.  Originally, traffic on I95 was predicted to back up all the way to Richmond (about 100 miles south of the bridges to DC) but there was absolutely no traffic in Richmond.

If you attended any of the inaugural events, please comment about your experience and the logistics.


betty crocker

This has nothing to do with OR, but I have a flair for cooking and I want to share the first edition 1950 Betty Crocker cookbook I inherited with you. I have never been a fan of Betty Crocker, since I like more flavor in food than just salt and pepper, but I find the 1950 edition cookbook fascinating. The recipes are actually more diverse than the subsequent edition Betty Crocker cookbooks, with ethnic recipes from all over Northern Europe. This was probably because of the high rate of immigration at the time. Don’t get excited about the diversity–mayonnaise is used in all of the salad dressings. I tried a couple of recipes from the cookbook and understood why most of the recipes were replaced in subsequent editions of the cookbook. However, the instructions for how to cook and dinner party advice are great. I’ll hang onto the cookbook for sentimental reasons and an occasional giggle, but I won’t try another recipe.

The most interesting aspect of the 1950 Betty Crocker cookbook is more than a collection of recipes, it is primarily a guidebook for assimilating to American cuisine and eating customs. These are my favorite excerpts:

  • Each chapter begins with serving instructions and cultural notes, presumably for immigrants. These explanations are a nice touch, and are missing from every other cookbook I own. Very little attention is paid to food presentation these days, and I must admit that I don’t have the time or inclination to make pretty meals.
  • The cookbook refers to the seven food groups (green and yellow vegetables; oranges, tomatoes, and grapefruit; potatoes and other vegetables and fruit; milk and milk products; meat, poultry, fish, eggs, and dried peas and beans; bread, flour, and cereals; and butter and fortified margarine). Yes, butter was actually a food group. Amazing. (The seven food groups were reduced to four in 1956, and the four food groups became a pyramid in 1992).
  • Betty Crocker recommends serving appetizers for “the hostess without a maid.” Was everyone that wealthy in the 1950s? (I have mixed feeling about this since the person who I got this cookbook from–Grandma–was a maid when she immigrated to the United States in the 1920s).
  • Betty Crocker likes eggs so much that wrote a nursery rhyme about them: “One, two–they’re good for you! Three, four–they taste like ‘more!’ Five, six–they’re fun to fix! Seven, eight–they’re mealtime bait! Nine, ten–here’s how and when! Eleven, twelve–dig and delve!” Now that’s enthusiasm for eggs!
  • Betty Crocker was not a vegetarian. She writes, “Without [meat], it is an unsatisfactory meal for most people.” However, she does recommend getting half of one’s protein from vegetables and grains. That’s fairly progressive by today’s carnivorous standard.
  • A single chapter (of 17) is devoted to vegetables. By comparison, there are 5+ chapters for dessert. Betty Crocker has a random musing about vegetables that turns into an odd value judgment: “[V]egetables are like people. By treating them with sympathy and understanding, they give us their best in color, nutrients, and flavor. Indifferent treatment, however, makes them drab and lifeless, their precious minerals and vitamins lost. Like people whose fine talents are wasted.”
  • When referring to adolescents (14-20 years old ): “A few pounds overweight at this period is an asset for health.” Enough said.

Amazingly, you can purchase a copy of the original Betty Crocker cookbook, and browsing inside this cookbook suggests that they have not changed a thing.


should I attend the Presidential inauguration?

I had been hoping to attend the Presidential Inauguration next week since it is in my backyard (DC is 95 miles from my house, and I have the option of taking a train part or all of the way). But since predictions for the number of people attending the inauguration events keeps climbing, I decided to stay home. Particularly since the last estimate I saw predicts that I95 will back up all the way to Richmond, meaning that I shouldn’t bother to even leave my house.

But more recent predictions by crowd experts indicate that predicted estimates are usually grossly inflated. After all, many people want to see a historically high turnout for the inauguration. Bigger is better, and big estimates signify the importance of the event in our culture.

Predicting the number of people who can attend the inauguration is a science, and it can be determined by asking these three questions, according to crowd expert Clark McPhail:

  1. What is the square footage of the available public space?
  2. What proportion of that space is occupied?
  3. What is the density ratio of that occupation?

McPhail indicates that simple geometry and points of view cause bad crowd estimates:

Large gatherings are usually more densely packed at the front and middle than at the back or sides. Estimates made from the front of the gathering and from a vantage point at or near ground level are victim to the perceptual illusion that the entire gathering is as densely packed throughout as it is at the front. This leads to the erroneous conclusion that the gathering is much larger than it more accurately appears when viewed from overhead. Organizers on a stage, looking at the gathering spread out before them, often fall victim to this illusion. So do inexperienced police observers and journalists.

The National Park Service is planning on having 5,000 portable toilets available on Inauguration Day. (I found this interesting, since I am no stranger to portable toilets–I reluctantly use one before every race I run. They key difference is that everyone goes to the bathroom at the same time before a race, where bathroom usage is likely more random at the Inauguration.) If one million people show up for the Inauguration, then there is one toilet for every 200 people and if four million people show up (the current inflated estimate), then there is one toilet for every 800 people. As Carl Bialik writes for WSJ, this is likely way too few toilets:

The New York City Marathon last November had one toilet for every 17 runners. The U.S. Army’s standard is one commode for every 25 males and one for every 17 females, according to Albin Majewski of the Army’s material systems directorate. And the International Code Council requires one toilet for every 40 people at nightclubs, and more than one for every 50 people in an office building.

Yeah, there is definitely some potty-parity going on. The average time spent in public restrooms is 47 seconds for men and 79 seconds for women. Most researchers find that women take about 70% longer in the bathroom and need more toilets. Bathroom science is fascinating.

So, now I don’t know what to do for Inauguration Day.  I want to attend the Inauguration (and it looks like I’ll be able to make it if I take the train).  But I’d also like to use a bathroom at some point during the day.


2009 Edelman Finalists Announced

INFORMS has announced the finalists for the 2009 Edelman Prize for achievement in operations research and the management sciences.  I can’t wait to hear more about these projects.  Details will follow soon, I presume.

  • Norske Skog, for Norske Skog benefits as O.R. plays a ‘pivotal’ role in the battle for improved profitability
  • CSX Railway, for CSX Railway Cashes in on Optimized Equipment Distribution
  • Marriott International, for Group Pricing Optimizer
  • IBM, for Analytics-Driven Solutions for Increased Sales Force Productivity
  • Zara, for Zara Uses Operations Research to Reengineer Its Global Distribution Process
  • HP, for Analytics for Product Portfolio Management


OR provides job satisfaction

Operations research is one of the best jobs!  This is unofficial, since “operations research” wasn’t exactly one of the 200 jobs ranked by CareerCast.com.  (What else is new?)  But you’ll find operations researchers in these careers that top the list:

1. Mathematician

3. Statistician

5. Software engineer

18. Computer programmer

The Wall Street Journal has a nice article about the list if you want to read more.  If you’re curious, “Lumberjack” came in dead last.


Follow

Get every new post delivered to your Inbox.

Join 2,464 other followers