You don't need to find oaks that don't produce acorns in order to measure how many acorns an oak produces. And, yes, if you measure 1000 acorns on a tree, you a

You don't need to find oaks that don't produce acorns in order to measure how many acorns an oak produces. And, yes, if you measure 1000 acorns on a tree, you actually do have an idea how many acorns are on that tree.