Name ______________________________
Date __________
Types of Sampling
AP Statistics
Do now:
The following diagrams represent different sampling techniques.
Look at each diagram
and try to determine what is being conveyed.
Every
combination
of
6
individuals
simple
Random
sample
srs
has
the
same
probability
of
being
selected
stratification
Homogeneous
grouping
Then
randomly
selected
cluster
Heterogeneous
grouping
Then
randomly
selected
3
groups
and
sampled
every
one
in
these
groups
Heterogeneous
grouping
Multistage
Randomly
selected
3
groups
are
randomly
selected
within
those
groups
systematic
chooseevery
nth

Vocabulary Toolkit:
Common Types of Sampling Methods:
•
Convenience Sampling
(see previous vocabulary toolkit for definition; not a very
good sampling method because it often results in bias)
•
Simple Random Sample (SRS
)
:
In an SRS, every combination of n people are equally
likely to be selected.
o
Ex.
Put all of the names of players in the NBA in a database.
Use a random
number generator to pick 12 players.
•
Cluster Sample:
When a population is divided into heterogeneous groups or clusters,
and then one
entire
cluster is sampled.
o
Ex.
Randomly pick three 9
th
grade advisories and survey every student in the
advisories chosen.
•
Systematic Sample:
A random starting place is selected, and then every nth
place/subject after that is sampled.
o
Ex.
Randomly pick one name in the phone book.
Then call every 100
th
person.
•
Stratification:
Divide the population into homogeneous subgroups (“strata”).
Then
randomly select a certain number of objects/subjects from each subgroup.
o
Ex.
Obtain a list of registered voters in a town.
Survey 10 people who are
registered Democrats, 10 people who are registered Republicans, and 5 people
who are registered as independents.