Without opining one way or the other about the young entrepreneur myth, is this the best metric to prove or disprove it? I'm assuming the "rate of entrepreneur

Without opining one way or the other about the young entrepreneur myth, is this the best metric to prove or disprove it? I'm assuming the "rate of entrepreneurship" means the percentage of people in that age range who are entrepreneurs. If that's the case, wouldn't the mid to older age ranges have an advantage, since people who started being entrepreneurs in their twenties, could conceivably still be entrepreneurs in their 30s and beyond? In other words, at the upper age ranges you're counting both people who just started being entrepreneurs as well as people who are continuing to be entrepreneurs. Whereas in the 20-25 age range, the only pool of people to count is the just-starting entrepreneurs. I think it would be more informative to show the median age of first-time founders. The article linked in this post mentions the average and median age for founders is 39, but in the context of this myth it makes a difference if that's a 39 year old first time founder or if he's on his seventh company and has been an entrepreneur since he was 19.