On Average

Roman Mars:
This is 99% Invisible. I’m Roman Mars.

Roman Mars:
Your world has not been designed for you. In large part, it has been designed for the average person. Throughout your education, you’ve been given standardized tests and been graded by how well you perform compared to the average. Building codes, insurance rates, the Dow Jones, all these measurements are based around the concept of an average.

Avery Trufelman:
And it’s okay, we know you’re not average. You’re really special.

Roman Mars:
Oh, thanks, Avery Trufelman.

Avery Trufelman:
Well, I mean it. You’re not average. No one is, not completely, but the concept of average affects us all.

Todd Rose:
Everything seemed to be based around this reference point of average and obviously everything about society is built this way, but I’d never really thought of it until I dug into this new science that we’re part of.

Avery Trufelman:
This is Todd Rose.

Todd Rose:
My name is Todd Rose. I am the director of the Mind, Brain and Education Program at the Harvard Graduate School of Education.

Avery Trufelman:
He’s also the author of the book, ‘The End of Average’, but to get to that, first we have to start with the beginning of average, because it wasn’t always a thing.

Roman Mars:
The concept of average as we know it was pioneered by a Belgian mathematician and astronomer named Adolphe Quételet.

Todd Rose:
So Quételet is the person who actually coins the term the average man, and in the 1830s, he is actually an astronomer in Belgium.

Avery Trufelman:
Today the way that most people get a handle on any set of numbers is to calculate the average, but in Quételet’s time, astronomers were some of the only people who did this.

Roman Mars:
Basically, averages were a way to compensate for the imprecise tools that astronomers were working with in 1830.

Todd Rose:
If you were trying to time the movement of Saturn, you would etch little scratches on your glass of your telescope, and as soon as it crossed one, you’d start counting, and you’d stop counting after it crossed the other and then you’d write it down. But you can imagine, even if you’re off by a half a second, it’s going to introduce a lot of error. And so they realized if they wanted to make sense of taming the heavens, they needed more precision in their estimates.

Avery Trufelman:
And they realized that if you had, say 10 measurements and they were all slightly different, if you added them together and divided them by 10, you’d get a better approximation of the true measurement.

Todd Rose:
If you just average together our measurements, you’re way more likely to be closer to the truth, right? And you end up getting kind of a bell curve of measurement errors.

Roman Mars:
Quételet was the first to take this tool of astronomers and apply it to people.

Avery Trufelman:
In the early 1840s, Quételet finds a data set of the chest measurements of 5,738 Scottish soldiers. Quételet added together each of the measurements and divided it by the total sum of the soldiers, and that result, 39-3/4 inches, was one of the very first times a scientist had calculated the average size of a human feature.

Todd Rose:
But he brings with it the idea of truth, that the average chess size is true and that all the individuals are error, that nature is striving for the average soldier.

Roman Mars:
This means the average measurement is the true measurement, the platonic ideal. The perfect Scottish soldier has a chest that is 39-3/4 inches according to Quételet.

Todd Rose:
So he’s the one that decides not only is average mathematically useful, it’s morally the way to think about people, and so he basically finds averages anywhere he can possibly find them, and he just has a field day.

Avery Trufelman:
He measures all kinds of other people and averages them. He creates something called the Quételet Index for measuring ratios of average height and average weight, and actually we still use it today. Just now, it’s called the body mass index or BMI.

Todd Rose:
Quételet would say if you talked about height, everyone if they were optimally fed, if they were under the same environmental conditions, would have been average, so his view was that what you’re striving for is the continual improvement of the average of the group.

Roman Mars:
And it wasn’t all just physical. Quételet combs through various datasets for marriages, murders, and suicides, and calculates the averages for them. He figures out there is such a thing as a normal suicide rate, which is really, really bizarre at the time, almost scandalous.

Todd Rose:
Nowadays when we’re so used to the stability of big massive amounts of data that it’s hard to put yourself in their shoes, but back then, they really thought that something like say suicide was such a personal decision that there couldn’t possibly be any pattern there.

Avery Trufelman:
But suddenly there were patterns of body size, of intelligence, of birth, of death. People became statistics. Their behavior starts to become predictable. Suddenly human life went by the numbers.

Todd Rose:
So obviously the first interpretation is, well, wait a minute, maybe there’s no free will, right? Maybe there’s laws of society just like there’s laws of physics, and so that kick-started a whole bunch of people like Karl Marx who loved Quételet.

Roman Mars:
And Quételet becomes a huge star. In his time, Quételet was up there with the likes of Sir Isaac Newton. His science of averages was this remarkable cutting edge way to assess the health, wellness, and progress of populations.

Todd Rose:
He’s really active in the 1820s, 1830s, 1840s, all the way into the ’50s and ’60.

Avery Trufelman:
And the 1860s brings us to the U.S. Civil War and to another super fan of Quételet’s science of averages, Abraham Lincoln.

Todd Rose:
When the Civil War is going in the North, Lincoln actually decides… I mean, they’re kind of getting their butt kicked, frankly.

Roman Mars:
In large part because this war had gotten so huge and unwieldy, Lincoln doesn’t really have a handle on the Northern Army.

Todd Rose:
And he’s like, “Look, we don’t even know who our soldiers are. We don’t know how well fed they are. We don’t know what kind of armor they need. We don’t know anything about them.”

Avery Trufelman:
Lincoln decided that the Union Army needed more information about its soldiers in order to best distribute resources, so he ordered this enormous study to assess the Union Army physically, medically, and mentally.

Roman Mars:
And then in explicit obedience to Quételet’s new science, averages were calculated and reported.

Todd Rose:
They actually say basically we’re following the father of this new field, Quételet.

Avery Trufelman:
These freshly calculated averages informed the distributions of food rations and the design of weapons.

Todd Rose:
For example, if you were going to create muskets, well, how far is the trigger, and you could actually calculate average reach for a soldier.

Roman Mars:
This also affected military uniforms, which used to be all custom sewn, but in the Civil War, so many people had to be outfitted that custom uniforms would be impossibly expensive, so the uniforms had to be mass-produced. But they couldn’t be just all one big floppy size.

Todd Rose:
And so now they’re realizing, ‘oh, well, you know, if we break it into subtypes, there’s a large, and this is what we mean by it, this big of a torso, this broad of shoulders; small, medium, large’, that’s going to carry over into the way they think about the mass production of clothing.

Avery Trufelman:
Yep. The sizes small, medium, and large, which might be on your T-shirt tag, those came out of this massive Civil War study. So you can thank Quételet and Lincoln for that.

Roman Mars:
This study in the Civil War was the basis for the American military’s longstanding philosophy of standardized average based design.

Todd Rose:
And that’s going to become the fundamental design philosophy from the Civil War forward.

Avery Trufelman:
So in 1926 when the Army was designing its first-ever fighter plane cockpit, engineers measured the physical dimensions of hundreds of male pilots and used this data to standardize cockpit dimensions. Of course, the possibility of female pilots was never considered. Of course.

Roman Mars:
The size and shape of the seat, the distance to the pedals and the stick, the height of the windshield, even the shape of the flight helmets, were all made to conform to the average 1920s male pilot, which changed the way the pilots were selected.

Todd Rose:
You basically would then select people that fit into that and then exclude people that don’t.

Avery Trufelman:
And this cockpit design worked okay up to World War II.

Todd Rose:
What happened was though is that in World War II, it became an Air Force war, right? That was the first time when the Air Force would be the determinant of who was going to win the war, and we absolutely ran out of pilots.

Avery Trufelman:
The government recruited hundreds of new pilots and expanded military aviation. They spent a bunch of money on fancy new planes, although the cockpits were still designed for the average 1920s male pilot.

Roman Mars:
And this new big, bad military force was going to fly the fastest and the highest and be the best.

Todd Rose:
But that’s not what happened. They actually had a pretty massive decline in performance, including just a rash of deaths.

Avery Trufelman:
Pilots were dying all the time. Even after the war ended, just in training, they could not control their planes.

Todd Rose:
It became kind of part of the culture of the Air Force where hey, it’s just really dangerous to fly.

Roman Mars:
No one knew what was going on. Some people thought, well, these ain’t propeller planes anymore. Maybe these new pilots just can’t deal with the new aviation technology.

Todd Rose:
And then they were like, well, maybe you got to train them better, and they did their better training programs and that didn’t work.

Avery Trufelman:
After blaming the pilots, the training programs, and the technology, it finally dawns on them what if it’s the cockpit? Maybe it doesn’t fit us anymore.

Todd Rose:
Their first instinct is to think, we’ve just gotten bigger as a people, so the old average from 1922 is just too small, right? We’re just bigger and badder, and let’s build a better average.

Avery Trufelman:
So in 1950, researchers at Wright Air Force Base in Ohio were tasked with finding this new average, and one of those researchers was a man named Gilbert S. Daniels.

Roman Mars:
Daniels was a Harvard graduate who had written his thesis on the average sizes of his classmates’ hands. He was 23 years old, small, skinny, nerdy, not a military man at all.

Todd Rose:
And he travels all over the country to different Air Force bases, and his job is to take these tape measures and just measure 147 different dimensions of body size. It’s got to be the most tedious job ever.

Roman Mars:
And as Daniels is traveling around from base to base measuring thousands of airmen, he’s realizing this incredible variability from person to person even within this limited demographic of young men.

Avery Trufelman:
As he was measuring hands and legs and waists and foreheads, Daniels kept asking himself, how many pilots were actually average? So he reports back.

Todd Rose:
So he goes to them and says, look, I think there’s a problem with the average, and he says, I just want to do this side study. I want to know if we take the 10 dimensions of size that matter most for design.

Roman Mars:
Like say shoulder with height, chest circumference, sleeve length, etc.

Todd Rose:
How many of these pilots are actually average on all 10 of those dimensions?

Avery Trufelman:
Daniels crunched the numbers, and of the 4,063 pilots, he measured, not a single airman was close to average in all of the 10 dimensions. None.

Todd Rose:
Not one, and it got even worse. If you just used three dimensions of size, less than 5% of the pilots were average on those. So he quickly realizes like, wait, now you know the problem. If you are designing something for an average pilot, it’s literally designed to fit nobody.

Roman Mars:
And in this new era of jet-powered aviation where pilots were making split-second decisions that could be life or death, it really mattered that pilots could reach what they needed to reach in the cockpit. The military sprang into action pretty much right away.

Todd Rose:
For the military to be willing to basically drop generations of design philosophy, right? Because it doesn’t take them more than a few years to just be like you can’t design an average anymore.

Avery Trufelman:
Air force engineers and contractors designed adjustable foot pedals and adjustable helmet straps and flight suits and adjustable seats.

Todd Rose:
You just can’t believe that we were building planes with no adjustable seats. That’s how much faith we had in the average person.

Roman Mars:
Once all the adjustable elements and other design solutions were put into place, pilot performance soared.

Avery Trufelman:
And of course, now we take this for granted that equipment should fit a wide range of body sizes instead of standardized around one average.

Todd Rose:
You wouldn’t buy a car that didn’t have adjustable seats, right? That’s just crazy, and it seeps into there pretty quickly in terms of automobiles, and then you see what’s interesting is the whole idea of ergonomics. That all comes off of this period of time.

Roman Mars:
World War II jump-starts the science of ergonomics, which is not just for office chairs.

Carisa Harris Adamson:
Well, it’s really the study of work is what you could boil it down to, but it really is a matter of matching people’s capacities to the job.

Avery Trufelman:
This is Professor Carisa Harris Adamson, Director of the UCSF/UC Berkeley Ergonomics Program.

Carisa Harris Adamson:
It’s really important not to go with the average a lot of the time. If we want to incorporate, say, a handle into something, well, we’ll look up the anthropometry data and make sure we identify the grip span that we think is best, or if we’re designing a crank and we want it to be at a certain height, then we will go back to the anthropometry data and figure out what makes the most sense to accommodate as much of the population as we can.

Avery Trufelman:
Keeping in mind that in the U.S., most of the measurements we base our designs on still come from the U.S. Army.

Carisa Harris Adamson:
And that’s primarily the source that we use in, say ergonomic books or when we’re designing for the workplace, and what we found is that those numbers are actually all pretty representative today except for weight and abdominal girth.

Roman Mars:
Which is part of why the world is so hard for heavier people to navigate.

Carisa Harris Adamson:
The military might be considered a more fit population than the rest of us.

Avery Trufelman:
So does this mean that military measurements affect the way our cars are designed?

Carisa Harris Adamson:
Absolutely. The measurements of our military personnel over the years affects just about everything.

Avery Trufelman:
Military measurements are the most public and accessible, and they work okay. They’re not perfect, sure, but they’re getting more inclusive.

Carisa Harris Adamson:
They’ve done a really good job in accommodating more of the population given that women are now a very vibrant part of our military force.

Roman Mars:
When the military opted to design for a greater range of people, they designed for a greater range of opportunity. Take, for example, Kim Campbell.

Todd Rose:
She was a fighter pilot and she flew an A-10 Warthog, and it’s worth Googling. It is the baddest looking plane you’re ever going to see.

Avery Trufelman:
That’s Todd Rose again, by the way, helping us tell the story of Captain Campbell.

Roman Mars:
In 2003, Campbell was sent on a mission to assist some Marines who were trying to take a bridge in Iraq. They were under heavy fire, but on her way back, her plane gets shot and she loses all control.

Todd Rose:
She has the option to eject right there and save her life, but then the plane spirals into Baghdad and kills a bunch of innocent people, so she says, I’m not going to do that. She stabilized it, which I don’t even know how you do, and she flies back and then she says, look, I think I can land this plane.

Avery Trufelman:
And she lands the massive, damaged, uncontrollable plane. It’s an incredible heroic feat, really unprecedented. So, of course, Kim Campbell gets awards and distinctions, and she is someone who could have never been one of the best pilots in the world had the military not changed their design philosophy.

Todd Rose:
She’s the beneficiary of a cockpit that’s flexibly designed because she’s like 5’4″ and rail-thin, and doesn’t look anything remotely close to an average-sized pilot.

Roman Mars:
When Kim gets into a cockpit, she has to put the seat all the way up and pull the pedals all the way out, but it fits.

Todd Rose:
This idea of equal fit as the foundation for how we think about real opportunity in society I think has serious consequences for the future of design.

Avery Trufelman:
And this concept that fit makes opportunity, it’s an important one for Todd because he believes that we can design environments and equipment and even entire systems to accommodate more and more people.

Todd Rose:
When we think about how we design environments, in a lot of fields we’ve made some progress around accommodating wider ranges of people, but actually in things like education, we still actually design for this mythical average person under the assumption that if you design something that fit an average person, it would actually fit most people.

Roman Mars:
By re-examining the concept of the average and acknowledging its limitations, we can maybe start to consider other ways of assessing and categorizing test scores or clothing sizes or wellness or happiness or worth. We can pave the way for more people who are outside of the average, because really no one is average.