January 2011 Archives


January 23, 2011

From my recently submitted comment to CBP
I recently re-entered the United States through the CBP International Arrivals checkpoint at SFO and wanted to share with you my observations about the way the checkpoint is configured. At least at the US Citizens side, passengers enter a single roped serpentine line that then fans out at the end to a large number of individual agents. However, because the serpentine line exits quite far from the agents' stations, this encourages passengers to form individual lines in front of each agent; I have also seen agents encourage passengers to do so. In my past three visits the lines at each agent have been between around 10 passengers deep.

Unfortunately, because there is a large amount of variation in how long any passenger takes to process, and likely in the speed of each agent, some lines inevitably move much slower than others, with the result that passengers who arrived earlier can get stuck in a slow line and end up actually being served quite some time behind a passenger who arrived later. On more than one occastion I have observed passengers switch lines when they realized they were in this situation. Once I even observed an agent leave for a break stranding passengers who had been waiting for him. Obviously, these are only minor inconveniences, but nevertheless they are annoying ones, especially when dealing with passengers who are eager to get home after a long flight.

The fix for this problem is simple and well-known: have passengers wait at the exit to the serpentine line and then pick whichever agent becomes open next rather than forming individual per-agent lines. In some cases, it also helps to have an agent at the end of the line to direct them if it is not otherwise obvious. This is, for instance, how things work at the customs checkpoint London Heathrow. I believe a similar strategy would represent a small, but significant improvement in the experience of passengers entering the United States at SFO.

BTW, the stranded passenger was me, but I figured that would just confuse things to mention. My point is structural.


January 22, 2011

Slate has published another Farhad Manjoo screed against unlimited Internet service.
And say hooray, too, because unlimited data plans deserve to die. Letting everyone use the Internet as often as they like for no extra charge is unfair to all but the data-hoggiest among usand it's not even that great for those people, either. Why is it unfair? For one thing, unlimited plans are more expensive than pay-as-you-go plans for most people. That's because a carrier has to set the price of an unlimited plan high enough to make money from the few people who use the Internet like there's no tomorrow. But most of us aren't such heavy users. AT&T says that 65 percent of its smartphone customers consume less than 200 MB of broadband per month and 98 percent use less than 2 GB. This means that if AT&T offered only a $30 unlimited iPhone plan (as it once did, and as Verizon will soon do), the 65 percent of customers who can get by with a $15 planto say nothing of the 98 percent who'd be fine on the $25 planwould be overpaying.

This seems extremely confused. First, it's generally true that whenever a business offers a limited number of product offerings with each at a fixed price that some people overpay because they only want some cheaper offering that the company doesn't provide. For instance, when I bought my last car, Audi insisted on selling me the "winter sports package" (heated seats and a ski bag). Now, I don't do a lot of skiing and I didn't want either but thats the way the thing came. Now by Manjoo's logic, it was unfair that I had to pay more for a ski bag I would never use (the heated seats are great, by the way) but that's just the way the product comes. Sure, I'd rather the company offered exactly the package I wanted but a limited number of offerings is just a standard feature of capitalism.

Its worth observing that there's nothing special about the "unlimited" plan in Manjoo's logic (It's not really unlimited anyway, since the network has some finite amount of bandwidth available so that provides a hard upper limit on how much data you can transfer in a month; it's just that that limit is really high.) Say Verizon offered only a 2GB plan, would he be whining that he only used 200 MB of bandwidth and so he was being made to overpay so Verizon can make money on the 2GB-using bandwidth hogs? So, this objection is pretty hard to take seriously.

Manjoo goes on:

But it's not just that unlimited plans raise prices. They also ruin service. Imagine what would happen to your town's power grid if everyone paid a flat rate for electricity: You and your neighbors would set your thermostats really high in the winter and low in the summer, you'd keep your pool heated year-round, you'd switch to plug-in electric cars, and you'd never consider replacing your ancient, energy-hogging appliances. As a result, you'd suffer frequent brownouts, you'd curse your power company, and you'd all wish for a better way. Economists call this a tragedy of the commons, and it can happen on data networks just as easily as the power grid--faced with no marginal cost, it's in everyone's interest to use as much of the service as they can. When that happens, the network goes down for everyone.

So, first this is just wrong: it's actually reasonably common for utilities to be included in people's leases and yet when that happens people don't automatically switch to plug-in cars or start up home aluminum refineries. That isn't to say that at having to pay for each watt of power doesn't have some impact on your consumption, but there is only so much power that it's really convenient for people to use; it's not like power being free causes consumption to spin off into infinity. To take another example, it's absolutely standard for local voice telephony service to be sold flat rate and yet practically nobody leaves their phone line tied up 24x7 just in case they want to say something to Mom and don't feel like taking the trouble to dial the phone. (Full disclosure, I actually have used dialup internet as a replacement for a leased line this way, but that's a pretty rare use case.)

The second problem with this claim is that computer networks don't behave the way the electrical grid does in the face of contention. Like the electrical grid, computer networks are sized for a certain capacity, but unlike the grid, computers aren't built with the assumption that that capacity is effectively infinite. If the electrical grid in your area is operating at full capacity, and you turn on your AC, this can cause a brownout because there is no way for the power company to tell everyone to use 1% less power and even if there was, many of the devices in question are just designed to operate in a way where they draw constant power. By contrast, computer network protocols are already designed to operate in conditions where they can't use as much bandwidth as they would like because non-infinite bandwidth is a basic feature of the system. Even if there is no contention for the network, applications need to work behind a variety of connection types so people who build applications typically build them to automatically adapt to how much throughput they are actually getting. For instance, Netflix has adaptive streaming which means that it tries to detect how fast your network is and if it's slow it compresses the media harder to reduce the amount of data to send. What this means is that unlike the electrical grid where your computer may just crash if it doesn't get enough power, if the network suddenly gets slower, performance degrades relatively smoothly.

The second thing you need to know is that in data networks congestion is (almost) the only thing that matters. If nobody else is trying to use the network right now then it's fairly harmless if you decide to consume all the available capacity. What's important is that when other people do want to use the network you back off to give them room. So, to the extent to which there is a scarce resource it's not total download capacity but rather use of the network at times when it's actually congested. To a great extent network protocols (especially TCP) already do attempt to back off in the face of congestion but there's also nothing stopping the provider from deliberately imposing balance on you (cf. fair queueing). In either case, this is a relatively orthogonal issue to the volume of data transferred; a cap on total transfer is an extremely crude proxy for the kind of externality Manjoo is talking about. Not only is it crude, it's inefficient: it discourages use of the network which would be cost-free for others and of value to the customer using the network.

All this stuff has of course been hashed out endlessly in the networking economics literature and the above is only the barest sketch. Suffice to say that just applying this sort of naive "tragedy of the commons" analysis doesn't really get you very far.


January 17, 2011

I recently concluded that I didn't have enough high-tech gizmos, and since a new car is really expensive, I decided to buy a new espresso machine instead. For the past 5 years or so I'd been uh, limping along with a Gaggia Espresso and a Gaggia MDF grinder, but it seemed like time for something new. (Those of you who are about to say "why can't you just use a Mr. Coffee like everyone else" can stop reading now.) After a bunch of research and a call to Chris Coffee I settled on a Quick Mill Silvano and a Baratza Vario grinder (total cost with accessories, around $1350). Now there's no doubt that this seems like a lot of money for a coffee maker, which it is, but let's actually do the math:

Consider two separate scenarios, both of which I actually have some familiarity with:

  • Home, both Mrs. G and I drink espresso at a rate of something like 2 shots/day each for a total of 4 shots/day.
  • Office, where we have something like 30 people sharing a single espresso machine. They probably drink around like 2 shots/day each for around 60 shots/day.

At home I buy either Four Barrel or Blue Bottle, both of which are just slightly more than $16/lb (454 g). A double espresso requires around 20g of beans, so in the best case with no lossage/sink shots you get 22 shots out of a bag of beans at a cost of around $0.70/shot. So in our home scenario we're spending $2.80/day ($1022/yr). If we figure the machine lasts 10 years, which isn't unreasonable for a good espresso machine, we're looking at another $140/year. In the office scenario we're spending $42/day, but only weekdays so around $8000/yr. You might be able to get a 20-30% discount buying bulk like this, but still we're talking around $5k/year in beans. You'd want a more expensive espresso machine for this use obviously, but even if you went nuts and spent $10K on the machine and grinder, you're still looking at only around $1000/year in capital expense (CAPEX) cost over the life of the machine. In either case you're looking at about 10-20% of your costs being CAPEX and 80-90% being operational expenses (OPEX).

What do these nubers tell us? First, it's a lot cheaper (and more convenient) to make your own espresso than it is to buy it. An espresso shot at Blue Bottle in the city goes for $2.50, so even if you live right next door and so there's no transportation costs, we're looking at a per-espresso price of between 1/4 and 1/2 that of retail. On the other hand we're looking at a relatively expensive caffeine delivery vehicle, comparable to buying every single soda you drink retail. That said, this applies to more or less every form of caffeinated beverage: bulk caffeine goes for more like $0.04/dose, as long as you're willing to deal with people looking at you like you're a meth addict when you tell them you take caffeine pills instead of drinking a 1/2-case of Diet Coke a day.

Second, as the vast majority of the costs are OPEX (and in particular supplies), so you probably shouldn't worry too much about your equipment costs (unless you're buying a Slayer or something). If you want to save some money you would do better to try to buy a cheaper brand of beans, negotiate a bulk discount, etc.


January 6, 2011

I'm probably like the 5000th person to point out the stupidity of this Macy Halford piece in the New Yorker about e-books:

The news made me feel like I'm not up to the challenges technology poses. Am I supposed to understand the desire of the Kindle to be held and read? Or the humans who prefer them to books? When I read a book all the way through to the end, I want the evidence stuffed and mounted on my bookshelf. My suspicion is that people who prefer e-readers use them primarily to read Harlan Coben, and are happy to be able to delete the physical evidence.

I had to look up Harlen Coben in Wikipedia, so I'm not sure what this says about Halford's taste versus mine. Regardless, I've read through plenty of books "all the way through to the end" (is this supposed to be some kind of achievement) and I indeed have them sitting on my shelf. However, that's primarily a function of not having anything more important to do with them, not of needing to display my reading prowess.

Really, it's not at all difficult to explain the appeal of e-books: it lets you carry a lot more reading material in a much lighter and more compact package. You would think that anyone who thought of reading as a pleasure rather than a chore would get that.

Obligatory Disclaimer: This isn't, of course, to say that existing e-books are perfect, just that the appeal of the concept should be obvious to anyone who likes to read.


January 3, 2011

Over the past few weeks I've flown three times through airports with the new whole body scanners (SFO terminal 3, SFO international, JFK terminal 2). JFK has the Rapiscan but they didn't seem to be using them at all—they were only in the priority line and a TSA agent was just standing in front of them. At both SFO security checkpoints, they had scanners (ProVisions at international, I don't remember in domestic) and they were using them. I'd been planning to actually decline the scan, but I didn't have to because in both cases they were only in some lines, so it was relatively easy to avoid them by picking which line you went into. At the international checkpoint, I actually had to cut across lines but nobody seemed to care.

If you actually want to get value from a security measure you need to ensure that people can't just bypass it. Consider the case of a terrorist carrying some device which won't show up on the magnetometer but will show up on the whole body imager; you just choose the line with the magnetometer.

Now, most likely the TSA is just getting started up here and eventually they will actually have scanners in every line and make everyone use them. After all, presumably they're not planning to have a bunch of scanners whose only purpose is be something for TSA screeners to lean against. What I'm curious about is whether at SFO TSA will give you the enhanced pat down if you refuse the body scan, since you could have evaded it easily without coming to their attention just by picking the right line.


January 2, 2011

I'm writing this from DL 133 en route from JFK to SFO and was pleased to see that this month Delta is offering free WiFi (sponsored by Google). As I usually fly United, any kind of on-plane Internet is a nice surprise. Still, I was amused to see the following when I tried to jack in on my iPhone from the gate:

It's a little hard to read but it says that inflight wireless doesn't work below 10,000 feet, presumably because using the Internet will make the plane crash, so they want to have plenty of time for you to be terrified as you plunge to your death. Of course, the whole reason I bothered trying to get WiFi on my iPhone is that my 3G performance was terrible, leaving me with the ironic situation that my Internet service is better at 30,000 ft over Iowa than on the ground in NYC.

P.S. This post was written on Thursday but posted on Sunday. Why? I reinstalled OS/X and it doesn't install iLife by default and I needed iLife to get the photos off my iPhone. That said, the new MacBook Air mini install USB key is pretty sweet.