How to use averages

We've had a baby; he's coming up for eight months now & I'm very fond of him. So far he seems to be be doing the things he should. He's nailed rolling over, is pretty good at sitting up and picking things up and while he hasn't quite got round to crawling, he's pretty close. I was apparently pretty retarded at those things, so he's up on me. He's a bit below average weight, and he's well below average for sleeping.

At least, I think he's below average for sleeping - neither standard baby books nor doctors tell you what the average is. I'm a big fan of averages, properly used of course - for example you really need standard deviation to understand cricket averages properly. In other areas, the baby profession is also keen on averages. They have very detailed tables of weight, height, and even head circumference and how it will change over time. It's therefore possible to worry, in detail, about the trajectory of your baby's weight gain, yet it's impossible to worry about his ability to sleep through the night (or rather, to worry about it with data). At the moment, I know which one I am more concerned about.

Depressingly, I think they do it deliberately. Weight is a lead indicator for health, so they have to track it, and they might as well get parents to do it. However, everything else may well be held back to avoid parental panic about how their baby is below average (we're guilty of this too; worrying the doctor about his changing weight position). Of course, just under half of babies are below average so, to put it another way, I have a horrible feeling we limit information to parents because we assume for they will fail to understand statistics properly.

On one level, I suppose this doesn't really matter, but what it means is that those of us who can understand stats don't get some useful information. For example, my boss has a baby about five months younger than JR, who already sleeps better. Good for him, but he needs to know that's better than average to calibrate his expectations of me (and others) who may not have such obliging offspring. On the other hand, A is of the opinion that being able to work out that you're in receipt of a baby that's in the lower deciles for sleeping is mostly depressing - there's not much you can do about it after all.

For me though, if there are numbers to be had, I'd like them. This of course isn't limited to babies, but with babies I think I'm right. It would certainly make conversations with parents on this subject less frustrating.