I think I found my answer here. http://www.xmarksthescot.com/forum/m...339/index.html in The Wizard of BC's post.

Now to just put it into place. It is suppose to hang straight from the waist but because of the "bay window" effect you have to take into account the extra window hanging over the hips.

I'm thinking that instead of leaning against a wall could I use a verticle level or a yard stick to make sure he is straight from belly to floor, THEN measure?