Its called the pythagoreom theorem (sp?)

Man I seen this debate for too long shooting on the 3-D circuit, everybody you talked to had a different opinion.

I think the most important factor is bending at the waste as someone has suggested. If you stay straight and bend with your arms or draw at a goofy angle things will change. I usually hunt 12-20ft up. I sight in on the ground. When I am in the stand I shoot the deer for the exact same yardage as I shoot on the ground. I also shoot for the center of the chest, this will give me the biggest variable for an inch or two up or down. Knowing yardage and your arrow drop is very significant in the later months when the leaves are off and you can add some yards. Does anyone know exactly how much their arrow starts to drop off from 25-30 a 30-35....you would be amazed, even the fastest bows can suprise you. I shot one event with my old bow and I had it maxed out and shooting a light arrow and chrono' ed at 323fps.....that thing would still bleed off energy and drop if I missed the yardage.