Where do standing height limits come from?

Just curious how they are formed, ie. are the test dummies a certain height and that factors into it?

I think some may come from dummy heights, and some others may come from percentiles (I can't remember which seat or company off the top of my head, but one convertible's rear-facing standing height limit was based on the 95th percentile for height for 3 year olds or something).

It's really too bad that the SureRide has a 40" standing height limit for RF. If it could RF all the way to 1" from the top of the shell, it'd be SO much more amazingly awesome than its already pretty cool self.

I wonder if there's any good reason for the limit? Why can't it be like the clones?

I hate standing height limits. When I was first researching convertibles, I kept looking only at seats with high rear-facing height limits and I was so frustrated because some of them only had the 1-inch rule and I had no idea how to compare that to my present-day child, whereas the standing height could be predicted with growth charts, etc. Then I realized that they ALL go by the 1-inch rule as well, so it's not practical to have a seat with both a standing height and a 1-inch rule because it just makes it harder to find a seat for a long-legged kid. To me, the way confused parents like me think, it's deceptive advertising to have a standing height limit because it gives the impression that the seat WILL last to that limit. I have yet to see any of the rationale for a standing height limit, from a safety perspective. The reasons for them seem arbitrary -- like the PP said about that one manufacturer basing it off of statistical data about child growth instead of statistical data about crashes. Why would I care if my kid were at the height of the 95th percentile for a 3-year old if I'm planning to rear-face to 4?

My kiddo is long-torsoed, so she will be outgrowing her infant seat soon. She's about 3-4 inches from the standing height limit of the seat, but she has only about 2 inches left of room above her head.

And the converse makes even less sense. Why on earth should it matter that my son's leggy legs are folded up in the seat pan when he has miles of shell above his head?