Normal is not the same as average

In this episode, we explore how a submarine, a car-door, and a chat about child-development led to useful insights about economics…

It had been a good conference, up in Sydney. Enterprise-architecture again, of course (you’ll find my slidedeck here, if you’re interested). Time to head back to where I currently live in Bendigo, in northern Victoria.

The Hume Highway that connects Sydney and Melbourne is a long, long, tiring road - fast, for sure, but more than 500 miles of uninterrupted tedium, where towns of any real significance can be an hour or more apart. I’d set out before dawn, but after a largely sleepless night, so by the time I reached the mid-point along the road, I’d realised was in urgent need of a break. Not safe to go on for much longer like this.

The next available pull-off point was the tiny town of Tarcutta, where just about everything was closed and boarded-up. Another victim of the pandemic, perhaps? - too many months without long-distance travellers like me to help pay their way? Either way, no help here: back on the road for a while longer yet.

After another half-awake half hour, the next turn-off sign at last came into view. Holbrook.

I like Holbrook. Just that little bit larger than other small towns along the road, with enough other industry to survive the loss of income in the pandemic. It has a nice big park in the centre of town, with easy parking, plenty of cafes around, and those all-important all-night public-toilets. And set slap-bang across the middle of the park, a hundred miles or more away from the sea, there’s a full-size submarine.

Yes, there is a real reason why it’s there. But since even small children are allowed to clamber all over it, it’s an absolute godsend for parents with kids who’ve been cooped up in the car for the past few hundred miles and who urgently need to let off some steam. Which kind of explains what happened next.

I pulled slowly into a parking-spot. I had to be a bit cautious, because on the next car over, the passenger-side door is wide-open: a young woman sitting there, side-on in the passenger-seat, holding a small child with a bottle in his hand. Feeding-time.

I carefully climb out of my car, making sure that the doors don’t clash. Which sets off a happy conversation.

The conversation soon drifts to talking about her son. He’s just under the one-year-old mark. No, he’s not her first, her other son is a couple of years older, he’s out there in the park with her husband, climbing up on the side-steps of the submarine. The two children are so different, she says - surprisingly different, at times. She doesn’t quite know if this is normal or not.

Actually, it is normal - I can reassure her on that point. My first job after leaving art-college, back in the early 1970s, was to work as an illustrator for a truly amazing woman named Mary Sheridan, who’d completely transformed the discipline of child-development studies in Britain and elsewhere.

Before Mary Sheridan, it was widely believed that all children did - or ‘should’ - develop in exactly the same way. ‘Normal’ was the same as average; a normal child was exactly on the average, in every way. Which led to just about every parent being either worried that their child was ‘below average’ in some way, or smug that their child was ‘above average’ in another. Or both, at the same time.

Sheridan demolished all of that. Yes, we could establish what ‘average’ looked like, for every different attribute, for every different age. What Sheridan did was to split those characteristics of child-development into four categories - posture and large-movements, vision and fine-movements, hearing and speech, social-behaviour and play - and then crossmap those averages by category and by age. For example, this illustration from her book shows the typical ‘large-movements’ characteristics for a three-year-old:

Illustration by Tom Graves in Mary D Sheridan, ‘Children’s Developmental Progress from Birth to Five Years: the STYCAR sequences’ (NFER, 1973)

Yet her crucial point was that normal is not the same as average. ‘Normal’ is not just the simple average across the board, but a pattern in relation to those averages: a normal child matches the average in relation to one of those four categories, but also one step ahead of the average on another category, and one step behind the average on the other two categories. And every child is somewhat different, and it’s all dynamic, sometimes going ‘backward’ just before a major move to the next step, or also when under stress, such as when the child is in hospital:

Illustration by Tom Graves in Mary D Sheridan, ‘The handicapped child and his home’ (National Children’s Home, 1973)

In short, if we compare our child with others of the same age, and we feel both a bit smug (because they’re ‘a bit ahead of average’) but also somewhat worried (because they’re ‘a bit behind average’), then probably everything’s just fine. It’s only if there’s a significant deviation from that pattern that any alarm-bells should start to ring.

By this point in our conversation, the young woman was looking a lot more relieved about her concerns - and said so. We then parted company, as her son had finished feeding, she needed to get back together with the rest of her family, and I needed to get some coffee into me before I keeled over.

On my way out of the cafe, though, she greeted me again, and introduced me to her husband, asking me to repeat what I’d said earlier about the patterns of child-development. That definitely helped, he said: he’d been a bit concerned because the three-year-old was a lot more shy and less willing to take risks than his younger brother, but he understood now that this was just natural differences in development, and unlikely to be anything to worry about.

Then he stopped, almost in mid-sentence. He was quiet for quite a while, clearly thinking hard about something, then turned back towards me again. “You know, that’s important for us too. At work, I mean. That bit about ‘Normal is not the same as average’.”

I asked him to explain.

“I’m in econometrics - how to measure success in economics, comparing company to company, country to country, quarter on quarter and so on. For us, it’s all about the averages. And normal is the same as average. Everyone wants to be ‘better than average’, everyone wants to be ‘better than normal’, ‘better’ than everyone else. But from what you’ve just said, then maybe that isn’t useful at all: it could be misleading us about what’s working and what’s not. We don’t look for the pattern, we don’t look for the dynamics - but we probably should. I’m going to have to think about that. A lot.”

Soon after that, though, it was time to go: we waved goodbye and went our separate ways. And that was that, really: just a nice, enlivening encounter, for all of us, in what would otherwise have been another tiresomely dreary day.

Yet I do wonder sometimes if that one small change in perspective - that warning that ‘normal’ may not be the same as ‘average’ - might someday lead to big changes in economics elsewhere. Given the current state of our world, I can only hope that it would be so - but it’s not up to me, of course. Or probably not, anyway…

———

Yet how about you? For enterprise-architects and others, how might the same themes play out in your own work and life? When dealing with metrics and averages, how much do you rely on an assumption that ‘normal is the same as average’? If so, how arbitrary is that assumption? What patterns of dynamic difference might be useful, in making sense of what’s going on in your organisation and elsewhere? What other useful lessons might we find from similar small-seeming changes in how we see the world?

Over to you for your own comments and experiences, perhaps?