Tuesday, March 10, 2009

How to Buy an Airline Ticket

Well, I can finally say I've attended an MIT lecture. Dr. Belobaba from MIT's International Center for Air Transportation (ICAT) dropped by today to give a guest lecture on the topic of airline pricing schemes and revenue management.

It was an interesting talk that did a good job of explaining why airlines feel the need to have multiple fares for the same flight and to sell tickets at different prices depending on when they're bought.

Basically, airlines want to sell as many high-priced tickets as possible, but they know that there are a lot of people who will only fly at lower costs, hence the need for differential pricing. Then of course, the people who were willing to pay more won't be quite as happy to part with their money if they know that someone else is getting the same service for the same price, which is why airlines introduced restrictions on low fare tickets including "Saturday night stay" conditions that prevent the type of quick round-trips that businesses require.

But on top of these differential pricing schemes, the airlines also use revenue management. That is, they reserve a certain number of the more expensive tickets based on statistical models for how many they believe they'll be able to sell. This is sensible enough, because if they know that they will eventually sell out a given number number of expensive tickets, they don't want those seats going to starving students who will only pay the cheap rate. Of course, they don't know how many tickets they'll be able to sell exactly, so that's where the probability comes in.

Technically, you look at the expected value of some probability function to do this, but all that means is that the cutoff for reserving a ticket of a certain class is the point at which you get the same number by multiplying the ticket's price by its probability of being sold as you do when you multiply the price of a cheaper ticket by its probability of being sold.

Anyway, what this all boils down to is that, first of all, you won't get the super cheap tickets months in advance, regardless of the probabilities, because airlines know they'll be able to unload those later relatively easily. The cheap tickets actually start appearing once the revenue management system kicks in and it realizes that the expensive tickets are being undersold. Now, if the expensive tickets are actually selling really well than you can forget about the cheap ticket and start wishing you had bought one before the prices tripled, however the upshot of all this is that given the statistical anomaly that is the current economy the model forecasts might be overshooting slightly.

Saturday, March 7, 2009

I'm Stupidly Full Right Now

As I mentioned in my last post, I was making pork chops for dinner. The grainy picture above, taken by my cell phone, shows the results. It was quite good and the actual cooking is really student friendly (it only has something like four ingredients) so I can officially recommend the recipe.

Rainy Day

It's Saturday evening and it's been raining all day. That's not really a bad thing; I've gotten some work and laundry done and a pair of pork chops are currently being simmered on the stove, so all in all it's been a decent Saturday.

Tuesday, March 3, 2009

If I Wrote a Textbook...

Figure 1: Godzilla looms over Billy.
Godzilla's foot is towering 0.3m above Billy's head. If Godzilla's foot weighs 200 kg and Godzilla's leg muscles exert a force FA of 30 Newtons onto the foot acting downwards at an angle of 30 degrees to the horizontal ground plane (see diagram), how much time does Billy have to move to avoid being flattened?

See now this is the type of problem people can relate to.

[Bonus: Write a differential equation expressing a werewolf's rate of change with respect to the phase of the moon. Use this equation to calculate how quickly someone needs to be locked in a cage once they start transforming, given that signs of werewolf behavior are detectable after the transformation is 20 percent complete. Use a safety factor of 1.2 and assume the lock is sturdy.]

EDIT: A few corrections for the first problem: assume that Godzilla's foot is large enough that it's horizontal motion in the brief time before impact can be neglected and that the foot will indeed impact Billy if he does not move. Furthermore, assume the foot has no velocity at the instant depicted in the question. Resolution of ambiguities in the bonus question are left as an exercise to the student, but be sure to state all assumptions and reasoning.

Sunday, March 1, 2009

Lots of Mayo

The above picture was of my brunch today. It's a tuna salad bagel plus some deviled eggs. I know it doesn't look particularly fancy, and compared to the stuff my housemates make (oven roasts cooked with wine, homemade chili, etc.) it's not that adventurous. However, I've had a bit of a phobia with hard-boiling eggs ever since I saw one of my previous roommates attempt it to disastrous results (yolk... everywhere...), so this is a something of a breakthrough for me. Also, it tasted delicious.

Ah, student cooking. Now if you'll excuse me, I need to go cook up some noodles for lunch tomorrow (we ran out of bread).

Crazy Random Happenstances

So I went on the band trip I was mentioning earlier. It was a good ol' time, going to a rival engineering school and playing with their band. I'll have that Maniac song stuck in my head for a while now.

You may also have recognized the phrase "crazy random happenstance" used in the title of this post as a line from the musical Dr. Horrible's Sing-Along Blog. It's hard to describe how cool this online musical really is -- I mean yes, it has an amazing cast, writers, and songs (many of which were recently blatantly stolen and rewritten for the university's Faculty, Alumni, Staff, and Students [FASS] Musical) -- but more than that, the DVD version has a musical commentary track. The awesomeness of this is mind blowing. Go grab some popcorn and have a listen!