I know the topic of Bradman's greatness has been done to death before, but the following video is too interesting to ignore.
In 9 minutes the Evolutionary Biologist Stephen Jay Gould explains why Bradman is unlikely to be better than Sobers, Richards, Lara and Tendulkar. Or if he is better, then only marginally.
Gould is American of course and therefore his theory centres around great batters in baseball, but it is still applicable to great batsman in cricket.
I won't claim to an expert in statistics so would welcome some comments (good, bad, or indifferent) from those who are.