SAMPLING TECHNIQUES
population:
ALL individuals who belong
to a group being studied
sample:
a SELECTION of individuals
from the population
Example 
Identify the population for each of the following questions:
a)
Who do you plan to vote for in the next provincial
election?
b)
Should we hold a prom next year at Mount Carmel?
There are many techniques used to select a sample from a population.
1.
SIMPLE RANDOM SAMPLE
 everyone in a population has an equal chance of being selected
eg.
2.
SYSTEMATIC SAMPLE
 go through the population sequentially and select members at
regular intervals
 interval = population size
sample size
eg. Much Music has 750 000 viewers. Design a systematic
sample if Much Music can only survey 500 viewers.
3.
STRATIFIED SAMPLE
 the population is divided into groups called STRATA (eg. age, sex)
 a stratified sample has the same proportion of members from each
stratum
eg. Before booking bands for the school dance, the student
council at MC wanted to survey the music preferences of the
student body. The school enrollment is as follows:
Grade
9
10
11
12
# of Students
425
410
370
455
Design a stratified sample for a survey of 25% of the student
body.
4.
CLUSTER SAMPLE
 the population would be organized into groups (eg. schools,
companies) and a random sample group would be chosen
eg.
5.
MULTI-STAGE SAMPLE
 uses several levels of random sampling
eg.
6.
VOLUNTARY-RESPONSE SAMPLE
 researchers invite members of the population to participate
eg.
7.
CONVENIENCE SAMPLE
 members of the population are selected as a sample simply because
they are easily accessible
eg.