chapter  16
58 Pages

Stratified Random Sampling

In many cases the universe being sampled can be divided into subdivisions and the sampling carried out in such a manner that each of these subdivisions is represented in the sample. When this is done, it is said that

stratified

sampling is being used. The subdivisions of the universe or sampling frame are known as

strata

. An individual subdivision is a

stratum

. Examples of such stratification are:

1. The divisions of a student body into two strata,

male

and

female

; 2. The divisions of pine stands on a certain tract into three volume classes or strata,

high

,

medium

, and

low

; and 3. The divisions of a forest ownership into its component administrative units, such as

compartments

.