tag:blogger.com,1999:blog-3829599.post116106451048390327..comments2024-01-28T00:20:40.933-08:00Comments on Agoraphilia: Fat StatsUnknownnoreply@blogger.comBlogger3125tag:blogger.com,1999:blog-3829599.post-1161396456487573572006-10-20T19:07:00.000-07:002006-10-20T19:07:00.000-07:00Brandon -- interesting! It's nice when someone ac...Brandon -- interesting! It's nice when someone actually has the data to answer a question. Well, not quite... as you say, there's a question of actual weights versus ideal weights. Still, it's nice to have something quantitative.<BR/><BR/>I think the way to address the problem, without making unjustified assumptions about the relationship between weight and health, would be to take non-weight-based measures such as clavicle-length or rib-cage depth and see how they correlate with height. That would give us a sense of how to account for changing proportions.Glen Whitmanhttps://www.blogger.com/profile/01425907466575991113noreply@blogger.comtag:blogger.com,1999:blog-3829599.post-1161297140339806352006-10-19T15:32:00.000-07:002006-10-19T15:32:00.000-07:00Blar, as far as I can tell, nobody has done any ca...Blar, as far as I can tell, nobody has done any calculation <EM>at all</EM> to justify the assumption that height-squared is the appropriate way to scale. We probably shouldn't assume that ideal tall people have exactly the same proportions as ideal short ones (we wouldn't expect them to have proportionally larger heads, for example). But a cubic function still seems like a much better approximation than a square function, given that humans have three dimensions all of which will tend to be larger for taller people. (Also note that the BMI doesn't use a baseline and square the proportional difference, but instead just squares the height directly. The formula is problematic all over.)<BR/><BR/>One thing I learned from the book is that the original BMI formula -- the one we still use today -- was devised by an actuary at an insurance company who noticed the correlation (not causation) between BMI and life expectancy. Of course, for insurance purposes, correlation is what really matters for the setting of premiums. So don't blithely assume that smart doctors and scientists put lots of thought and research into this. There's a shockingly large amount of sheer arbitrariness involved in the field of "obesity research."Glen Whitmanhttps://www.blogger.com/profile/01425907466575991113noreply@blogger.comtag:blogger.com,1999:blog-3829599.post-1161293978711699312006-10-19T14:39:00.000-07:002006-10-19T14:39:00.000-07:00...so long as their bodies are proportionate to th......<I>so long as their bodies are</I> proportionate <I>to their height</I>.<BR/><BR/>Glen, if you think that this is what's wrong with the BMI then I've got a <A HREF="http://www.sphericalcow.net/why_sphericalcow.htm#joke" REL="nofollow">spherical cow</A> to sell ya. You can't top its milk production.<BR/><BR/>The point being that the other two dimensions of a person <I>don't</I> increase proportionally when people grow taller, or at least they aren't supposed to. Some people have decided that height squared is a decent approximation to account for the increase in width and breadth, and maybe they're wrong, but that's something that you have to decide based on data about the actual shape of human bodies, not pure math.Blarhttps://www.blogger.com/profile/17654557196171228300noreply@blogger.com