DirtyWorks said:
I agree with you, but it would be an interesting exercise to categorize the years by the number of days racing and see what happens to ages. I don't think it changes your conclusion, but would like to see anyway. What discourages me from working on it is apparently the racing days changed in an inconsistent way.
Of course, the introduction of EPO and later is not reliable data.
Well that's the fascinating thing about the data. Since the average age and distribution remains the same from first Vuelta to 2012 (you really should graph the data!), then you can conclude that no matter what has changed through the years (roads, bikes, days racing, drugs, training methods, etc, etc, etc) it has not had an effect.
From that you could go "A ha!" and state that since drugs like EPO have not had an effect on average age of a Vuelta winner then drugs could not have been the cause of Horner's miraculous victory.
So whatever is driving Horner's performance must be relatively new, or we would have seen the ages trending upwards since the EPO era. From what we know about aging, endurance performance declines at a predictable rate from late 20's onwards. Horner has done something to counteract that decline, and the only reasonable inference is that it has been done medically. I.e., he's doping and doping real hard whatever it is.
CAVEAT: This inference and "conclusion" regarding doping is barring any new data which would explain such a heavy influence on age related decline.
John Swanson