Sample Design
2-1
Sample
 Subset of a larger population
Population
 Any complete group
 People
 Sales people
 Stores
 Students
 Teachers
Census
 Investigation of all individual elements that make up a
population
Sampling Frame
A list of elements from which the sample may be drawn
Such as
 Mailing lists
 Commercial directories
 Telephone directory
 Databases
Categories of Sampling
 Probability sampling


Known chances
Every member gets a chance
 Nonprobability sampling

Unknown Probability of selecting any
particular member
Nonprobability Sampling
 Convenience
 Judgment
 Quota
 Snowball
Convenience Sampling
 Obtaining the people who are most conveniently
(readily) available
Judgment (purposive) Sampling
 An experienced individual selects the sample based on
his/her judgment about some characteristics required
of the sample member
Quota Sampling
 Various subgroups in a population are represented on
relevant sample characteristics according to
researchers desire
Snowball Sampling
 Initial members are selected
 Additional members are selected based on
information provided by the initial participants
2
1
1
3
Probability Sampling
 Simple random sample
 Systematic sample
 Stratified sample
 Cluster sample
 Multistage area sample
Simple Random Sampling
 Every member of the population has an equal chance of
being selected in the sample.
Simple random sampling
Systematic Sampling
 A simple process
 Every nth name from the list will be drawn
Systematic sampling
Stratified Sampling
 Subsamples are drawn within different strata
 Each stratum is more or less equal on some
characteristic
What is the right stratified sample?
Cluster Sampling
 Dividing the population into groups, or clusters,
 Selecting some of these clusters at random.
 Obtaining the sample by choosing all the
members within each of the selected clusters.
Cluster sampling
Section 1
Section 2
Section 3
Section 5
Section 4
Examples of Clusters
Population Element
Possible Clusters
Airline travelers
Airports travelers
Planes travelers
Sports fans
Football fans
Basketball fans
Car race fans
Karate fans