Why do biologists use Sampling?

Question

Why do biologists use Sampling?

Answer 1

Because there is no way to test all individuals of a specie. It is virtually impossible to run a test on all human beings, all mice, all cats, dogs, .... in the world. Therefore when running an experiment, a small group of a specie is randomly selected to be tested. This small group is a "sample" that represents the whole population of that specie, and the process of selecting this group is called "sampling".

Answer 2

Take for example estimating fish populations.

What biologists will do is to simply take a sample of the population by grabbing up about fifty fish and marking them somehow.  The amount grabbed is a certain percentage of teh entire stock of the given area.  Say for example that 1000 fish live in a lake.

They will then go back out after a given length of time and scoop up a random sample of fifty fish, the number that they marked.  If they get back fifty marked fish, it means that the population has probably not grown at all, and even diminished.  If they get back only one or two marked fish, they know that the population has grown immensely.  They conduct many catchings to get a variety of trials.

If after ten trials the biologists still get back all fifty marked fish, it could mean that the population has been dimished to only fifty fish.  If they continue to pull up only one marked fish, it could mean that a fifty times the beginning amount of fish live in the lake now.

These variables can be changed to amass data in different amounts.

Sincerely,

G.C.