This is a careful selection of part of the whole environment to be studied to represent a whole or a larger environment. It is used by random picking or sample collection of specimen of soils, fish, crops, etc.

 

Advantages:

Provides a representative sample that enables the study of a large area.

First hand information is acquired

It is timesaving since a small part of a whole is taken to represent the whole.

It is easy to apply

Disadvantages

Selection of a sample which is not quite representative of a wider area

Sample may be biased

Unrepresentative samples make it difficult to use the findings for general conclusions.