How are large numbers of things like the human population or the number of a particular type of fish in the ocean calculated accurately?

Question

Does it have anything to do with statistics? Are they actually accurate or just estimates? How much variability is acceptable in case of an estimate? And how do they calculate what the human population was, say, 3000 years ago? I guess I’m trying to ask how large scale censuses work.

In: Other

Answer 1

For wildlife (plants and animals), it’s often estimated based on samplings.

For example, a researcher looking to find numbers of plants in an area may lay out a line of 100 meters, and walk along that line, counting all the plants of type X that she sees. Then, she’d repeat that several more times to get an idea of the frequency of that particular plant in that habitat. The numbers would be estimated off of that.

For animals, techniques can include tagging and releasing, then recapturing animals later on, motion activated cameras, etc. In all those cases, the goal is to get an estimate of how common the animal is – there’s no way to get an exact number.