Raymond Martin

rmartin@utech.edu.jm

Lecture 7 – Sampling

Data are collected to represent a population or study area.– A census is complete enumeration of the population

while

– sampling uses part of the population to make conclusions about the entire population

Lecture 7 – Sampling Cont’d

Lecture 7 – Sampling Cont’d

Lecture 7 – Sampling

Two types of sampling:

– probability or random

– non-probability

Lecture 7 – Sampling

Probability sampling:

– no bias; equal probability of subjects being selected

– sample frame required - list of study subjects or picture/aerial photograph from which sample selected – maps or aerial photographs may be used.

Lecture 7 – Sampling

Probability sampling:

– simple random

– systematic – stratified

– cluster