Archive for the ‘society’ Category

Earth to Humans: You’re Doing It Wrong.

April 24, 2012

Here’s my Earth Day article. You may notice it’s late. That’s because I didn’t realize it was Earth Day until a few hours after midnight when somebody said something dumb. Here it is:

The founder of a popular British festival has even said that he would consider powering the event on beer piss, should science find a way. Don’t laugh — human beings collectively produce around 6.4 trillion liters of urine a day, so an effective way of harvesting energy from this golden wonder-fuel might end our fossil fuel dependency overnight, as well as mitigating the effects of one more way we go about polluting the environment.

We do not produce 6.4 trillion liters of urine a day, even on a steady diet of coffee, alcohol, and the vague first-world boredom that leads to a bathroom break every half hour or ten games of Draw Something, whichever comes first. The 6.4 trillion figure is around 250 gallons of urine per person per day. If that were so, your urine would fill two midsize cars every week. At an average flow rate of 20 mL/sec, you’d have to pee for fourteen hours every day to get it all out.

That’s the dumb part – a silly gaffe. But there’s a stupid part, too. You can’t get more energy out of beer urine than you can get out of beer. You can’t get more energy out of beer than you can get out of beer plants. You can’t get more energy out of beer plants than you can get from the sunshine they absorbed. Processing your sunlight by way of a barley seeds, the digestive system of yeast, and a human liver is, as a thermodynamic strategy, piss poor.

Humans are not energy producers. Any energy we output came from our food and represents our bodies’ inefficiency. Only a fraction of the energy we eat can be reharvested, and the energy we eat is about one percent of the energy we use on all our gadgets and things. Measured purely by energy consumption, it’s as if every person in the US has 100 personal servants. Recapturing energy from our bodies is like realizing our 100 servants are too expensive, so we make one of them give us a percent or two of their wages back. That means we can only ever get a miniscule fraction of the power we need from any human activity – urination, generators inside exercise equipment, piezoelectric thingymabobbers in the floor, engines run on body heat, etc.

Even if you crush your enemies and drive them before you, the lamentation of their women will not provide much power.

Why bother, then? Why is there a dance club whose floor generates electricity for lighting as revelers hop around on it? Why don’t they just dance during the day?

Human-generated electrical power could make sense in special circumstances – charging your bicycle light with energy from the bicycle, for instance, but as a general plan it’s insane. The floor in that club is not about generating electricity. It’s very unlikely that the energy generated could ever recoup the cost of the installation – if you exercise for an hour, you’ll generate around a penny worth of electricity, and that’s with high efficiency. Instead, the floor is about advertising that it generates electricity.

This is what we’ve done with energy conservation – made it into a luxury item more about social signalling than ecological benefit. How many people, proud of their environmentally-conscious Prius, have any idea how much energy went into the car’s manufacture? How many of them drive it alone? (Though Prius owners may deny it, the car’s popularity is mostly about social signalling. For cars that come in gas-only or hybrid variants, the hybrids don’t sell well. If it’s not a hybrid-only brand, it’s a lot harder for people to recognize how environmentally-conscious you are.)

No one would tie a helium party balloon to a hippopotamus and say, “See? I did my part to help it fly!” Yet they feel just like that when they bring their own bags to the grocery store. On Earth Day, people turn their lights out for an hour. (Did that happen this year? Or is it some other day? Whatever.) If everyone turned all their lights out in their homes all the time, it would reduce power consumption in the US by about two percent.

The lights-out thing is symbolic, of course. It’s there to remind you of the importance of energy conservation, and to show other people you think energy conservation is important. The problem we’re facing is that everything is symbolic – our efforts at conservation are almost random, showing no systematic effort to focus on the big-ticket items, or even knowing what they are. How many cell phone chargers would you have to unplug to make up for the energy spent on one cross-country plane flight? Most people don’t know, and so most effort put into energy conservation is wasted.

Worse, if you’re conserving energy because you want the warm fuzzies associated with it, you get your warm fuzzies based on how much you inconvenience yourself and how much you show off, not on how much energy you actually save. You feel just as good about unplugging cell phone chargers as deciding to stay local on vacation. Our emotions have no sense of scale.

Even worse than that: when we talk about energy conservation and environmentalism, we’re largely bullshitting, and people pick up on that. That’s the thing with signalling to your tribe. It gets the other tribe pissed off. (And as we’ve learned, piss is not very productive.) The worst part about energy conservation and environmentalism is that they’ve been wrapped up into one issue and shipped off to the place where good debates go to die – politics.

If we could separate our conservation efforts from our warm fuzzies, we’d send out fewer of the pheromones that rile up political associations and drive out even the possibility reasonable discourse. Fewer news stories. Fewer buzz words and applause lights. More Sustainable Energy Without the Hot Air and The Azimuth Project. That is how you get a hippopotamus to fly.

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My Peers’ Birthdays

May 18, 2011

follow-up to My Friends’ Birthdays

The main conclusion I drew from examining my Facebook friends’ birthdays is that I didn’t have enough data to see the birth month effect – when your month of birth influences your success in a field because it decides your relative age to your peers early on in sports or school.

The birth month effect is real in some circumstances. Just now, I searched for “US junior baseball team” and found this roster.

In Outliers, Malcolm Gladwell explained that the cutoff date for youth baseball leagues in the US is July 31. (It’s now changed to May 1, so in ten years we can do this experiment over and see the effect.) Thirteen players on the roster were born in the half of the year directly following July 31 (August through January), and only five were born in the next half (February through July). With data like that, even a sample of eighteen people is enough to see the strong effects that birth month has on athletic success. The odds of such lopsidedness occurring by random chance are about 5%.

If 18 baseball players is enough to see a significant birth month effect in sports, then shouldn’t more than 100 Facebook friends have been plenty to see it in education?

In American education, there is no firm, uniform cut-off date like there is with baseball. Different states have different dates. Also, parents may have a choice about when to send their child to kindergarten if the child is born in a certain window. I was born in December in Maryland, where entering kindergarteners must be five years old by December 31. I could have been one of the youngest students in my grade, but my parents held me back, making me one of the oldest. Their stated reason was that they thought I’d appreciate being one of the first kids with a driver’s license come high school.

Mixed-up birth months, along with other obfuscating factors the reader may imagine, could easily make a real signal difficult to pick up, so I asked the Caltech registrar’s office for data on all the domestic Caltech students. They kindly obliged, with birth months tallied for the 5083 students enrolled since 1985. I was asked not to release the data directly, but I can report on its statistics.

Since September to December babies can be either old or young when entering kindergarten, let’s leave them out. The hypothesis is that entering Caltech students are more likely to be born in the January to April time frame than May to August. (If you want to be a stickler for experimental design, we could say that the null hypothesis is that students are equally likely to be in those categories.)

There were 3399 students whose birth months fell into one of these two ranges. If each student were a simple binomial variable with even probability we’d expect a standard deviation of 29 in the number of students in each range. We should also take into account that these periods aren’t perfectly equal in numbers of births. According to a Google result, a baby born anywhere from January to August has a 51.85% chance of being born in the May-August window, due partially to the three extra days and partially to higher birth rates. Thus, we expect that if domestic Caltech students have birth month patterns that mirror the American population at large, there should be 1762 +/- 30 students born in the May-August window. If there are fewer than 1700, we have evidence that Caltech students are less likely to be born in the summer.

The statistic is 1713 born in those months, compared to 1686 in January – April. The discarded period, from September to December, has 1684. There is no significant evidence to suggest that Caltech students are more likely to be born in any particular month.

This certainly doesn’t disprove the idea that your month of birth impacts your success in school, but the effect, if present, is not as powerful in education as it is in organized sports.

My Friends’ Birthdays

May 2, 2011

Malcolm Gladwell’s Outliers describes how elite hockey players in Canada are far more likely to be born in the first half of the year than the second. There’s a simple explanation – Canadian youth hockey leagues bin age group teams according to the calendar year of birth. Two young players, one born January 1, 2003 and the other December 31, 2003 are considered the same age and play in the same league.

Being born in at the beginning of the year makes you a few months older than most of your peers. When you’re eight year old, those few months equate to a big advantage in physical maturity. Being more mature, you perform better, get selected for elite teams, and receive better training. You get better and better while your peers born near the end of the year are left behind.

The data shown in the book are convincing. The phenomenon is seen not just in Canadian hockey, but in a host of other sports where a similar age cutoff exists, and when the cutoff date changes from January 1, the distribution of birth months changes, too. (Basketball in the US is one exception, presumably because kids learn on the streets regardless of their birth month, and don’t need to be selected for elite training until later on.)

Then Gladwell goes on to suggest that the same effect dominates academic achievement in the US.

Parents with a child born at the end of the calendar year often think about holding their child back before the start of kindergarten: it’s hard for a five-year-old to keep up with a child born many months earlier. But most parents, one suspects, think that whatever disadvantage a younger child faces in kindergarten eventually goes away. But it doesn’t. It’s just like hockey. The small initial advantage that the child born in the early part of the year has over the child born at the end of the year persists. It locks children into patterns of achievement and underachievement, encouragement and discouragement, that stretch on and on for years.

Recently, two economists — Kelly Bedard and Eliza­beth Dhuey—looked at the relationship between scores on what is called the Trends in International Mathematics and Science Study, or TIMSS (math and science tests given every four years to children in many countries around the world), and month of birth. They found that among fourth graders, the oldest children scored somewhere between four and twelve percentile points better than the young­est children. That, as Dhuey explains, is a “huge effect.” It means that if you take two intellectually equivalent fourth graders with birthdays at opposite ends of the cutoff date, the older student could score in the eightieth percentile, while the younger one could score in the sixty-eighth percentile. That’s the difference between qualifying for a gifted program and not.
pp 28

The first paragraph seems like a rather wild extrapolation, based solely on the second.

I wanted to know if I could see this birthday effect in some data I had readily available – that generated by my Facebook friends.

I have about 700 Facebook friends, many of whom were Caltech students. These people represent an academic elite, so if the birthday effect is extraordinarily strong, I ought to have friends whose birthdays come in a clump, assuming they are educated in the US.

I tallied the birth months of all my Facebook friends who are or were students at Caltech and who listed themselves as being from somewhere in the US. (I wound up throwing out a lot of people from the US because they didn’t list a home town, but I thought it was better to have a uniform data collection policy than to guess.) 110 people made the cut.

I made a plot of their birth months, and it looked like maybe there was some sort of signal in there. So then I made seven fake plots by randomly generating birth months from a flat distribution. Here are the eight plots. Can you tell which one is the real data?

One of these plots is real data from the birth months of students at one the world’s top universities. The other seven plots are as random as Python can make them. I challenge Malcolm Gladwell to tell me which one is which.

This challenge is a bit unfair. What I really ought to plot is not birth month, but age when starting kindergarten. These aren’t the same, largely because people born near the end of the year (like me) can wind up either old for their grade or young for it. Still, January babies are almost uniformly old for their grade in the US, and August babies are almost uniformly young. If the effect is as powerful as Gladwell suggests, we ought to see it at play here.

If birth months were evenly distributed and I took 110 data points, the expectation value for a each month is 9.2 and the standard deviation is 2.9. Since the standard deviation is pretty big compared to the expectation value, we would need a large signal in order to see an obvious effect in the data. So to make a strong case, I really ought to have more data.

Still, we actually expect whatever effect there is to be magnified when looking at this data. The reason is that, with Caltech students, we’re looking far out on the tail of the distribution of academic ability.

Here are two normal distributions that are the same except that one is shifted to the right.

The original gaussian, centered on zero, represents students born late in the year, and the shifted one represents students born near the beginning. (This is only supposed to be a heuristic, of course.)

I’ve added two vertical lines. The first vertical line shows a cut off for students who are “good at school”. There are about three times as many students from the shifted distribution that make it beyond this cut off.

The second line shows students who are “very good at school”. There are about ten times as many students from the shifted distribution that make it beyond this tougher cutoff.

Even though I don’t expect the age-selection effect to work in such a simple way, the main idea is simply that if you give one population a small advantage over the other, the effect becomes magnified when you look at the frequency of outliers. So, in the birthdays of my Caltech friends, I ought to see a pretty strong signal, if the basic effect exists.

So, for now I’d say that, lacking further data, either the effect is not very large, or it is not very simple, so that somehow it allows Caltech students form an exceptional bunch.

We Need a Power Pyramid

May 22, 2010

You know this thing, right?

USDA food pyramid

Thanks to the food pyramid, which almost all Americans recognize, we basically know what healthy eating is. You can find a lot of bickering about the details. You will even find some nutritionists who claim everything about it is wrong, but they are sensationalists.

It’s not complicated, it’s important information, and basically right. Eat lots of plants, fewer animal products (Don’t hate, vegetarians. “None” is a special case of “fewer”.), and only a little junk food. Most Americans pretty much know what healthy eating is. (Knowing what it is is quite different from doing it!)

I think we need one of these for energy consumption. We seem, as a nation, to be out of touch with the basics on this, and like the food pyramid, it’s important and it’s simple. Everyone should know the basics about energy the same way they do about healthy food.

I recently heard earnest praise of the iPad because by reading books on it, or using it as a scratchpad, it saves paper. That’s true; the iPad saves paper. But remember, homicide cuts down on traffic congestion. So I started trying to calculate which is better on environmental terms – books or iPad. I estimated that reading books sustainably winds up taking a lot more ground space than generating the energy to manufacture and use an iPad. Then I googled and found an article from the New York Times with a similar goal, but its conclusion was that once you read more than a few hundred books, the overall impact of the iPad is significantly less than buying new books. Now what do I do?

I want to use less energy, but it’s irrational to go to all ends figuring out every last thing about doing it. It doesn’t matter which choice I make because the energy involved in using an iPad or reading the books is very low when compared to more significant types of consumption.

When thinking about conserving energy, we are pretty dumb. We spend far too much attention on things that are visible, immediate, and easy to understand, rather than things that are significant. Unplugging your cell phone charger when not in use to reduce power consumption is like going to New Orleans after Hurricane Katrina and helping re-sort someone’s sock drawer.

Magazine articles that calculate the gallons of water saved if you run the faucet for 15 fewer seconds while brushing your teeth are missing the point. Why bother brushing your teeth in tiny little spurts of water from the faucet if you are about to take a hot bath? And a hot bath pales in comparison to watering your lawn. Don’t stop brushing your teeth. Stop watering your lawn.

My calculation about the iPad and similar calculations are dangerous. Even if they’re correct, they encourage us to focus in the wrong direction. There are hundreds of similar minutiae I could worry about. Metal forks or recyclable bio-forks at the cafeteria? Paper or plastic at the supermarket? How much energy do I use when downloading a porno?

To be realistic, you are only going to worry about energy consumption a certain amount. After that, you’ll have to get on with your life. Spend the worrying where it counts. In order to do this, we need to know what counts and what doesn’t.

For this, I highly recommend David J. MacKay’s Sustainable Energy – without the hot air, which you can download for free at the link. He gives a clear, straightforward account of how we use energy and how we can potentially generate it.

Take a look at this graphic, for example:

From David J. MacKay's 'Sustainable Energy without the hot air' pp. 204

Current consumption per person in cartoon Britain 2008 (left two columns), and a future consumption plan, along with a possible breakdown of fuels (right two columns). This plan requires that electricity supply be increased from 18 to 48 kWh/d per person of electricity. (MacKay's caption)

This is really good – clear and informative. MacKay’s book contains many fantastic charts, plots, and graphics visualizing energy consumption and generation.

This graphic, though, is for people who are reading an entire book about energy. That makes it for a minority. We need something simpler and more iconic, like a food pyramid for energy consumption.

It may also be useful for the graphic to show not total consumption, but how much energy can be saved by cutting back in certain areas. Cutting back in transportation energy is easy and huge potential benefit. That goes on bottom. Turning off the lights is a very small thing by comparison. That goes in a tiny little triangle on top.

One difficulty is that the power pyramid is dependent on the people it’s targeting. Here in the San Francisco Bay area, I use almost no power for heating because the weather is nice. Also, living in Berkeley, a bicycle-friendly city with good public transit, I choose to forgo a car and use very little energy for transportation. Someone living in rural Wisconsin will naturally have a very different pyramid than I will.

We’ve gotten to where most people know that we’re using too much energy, but we have a lot of work to do in consolidating the message. We need a simple, effective, clear image, like the food pyramid, that can be put where people will see it hundreds of times, and burn in the basic idea. As MacKay points out, the slogan “Every little bit helps,” is not this message, and is in fact its antithesis.