[miraja2]

In fact, I believe the way to do this that makes the most sense is simply to examine the average field size of all three races for every single year. Then you could identify trends between "TC decades" like the 1940s and the 1970s, and compare them to the last 25 years and see if the data is important.
Here is why: Field size COULD be responsible for preventing a horse from winning the TC even if that horse didn't win the Derby AND didn't compete in all 3 races.
For example, in recent years horses such as Empire Maker and Birdstone did not win the Derby, skipped the Preakness, and then won the Belmont. It is pretty safe to assume however that if those horses had won the Derby, they wouldn't have skipped the Preakness. I am not saying that either of those two lost specifically because of field size, BUT the field size of the Derby in these years is just as important as the field size in the Belmonts from those years that "prevented" Funny Cide and Smarty Jones from winning.
My response to Cajungator26 was based solely on her argument that we should NOT consider horses that won two of the other legs but not the Derby. My argument there was that IF we were limiting the discussion to horses that won 2 out of 3 legs, then it only made sense to consider horses that won any of the 2 legs. If, however, we are not limiting it in that way (which, as easy goer correctly points out, makes the most sense) then I think it only makes sense to always examine the field size of all three races for every year.
I have now officially spent WAY too much time on this thread.