If you told marine biologists to measure the fish in the lake, they would not confuse a “count” with a “measure.” Instead, the biologists might employ a method called “catch and recatch.” First, they would catch and tag a sample of fish—let’s say 1,000—and release them back into the lake. Then, after the tagged fish had a chance to disperse among the rest of the population, they would catch another sample of fish. Suppose they caught 1,000 fish again, and
