Sampling Designs

1
Chapter 4 Sampling continued

• Sampling Designs
• and Procedures

2
Two Major Categories of Sampling

• Probability sampling
• Each element of the population has a fixed
  probabilistic chance of being selected for the
  sample
• Nonprobability sampling
• Relies on the personal judgment of the
  researcher.

3
Nonprobability Sampling

• Convenience
• Judgment
• Quota
• Snowball

4
Convenience Sampling

• Also called haphazard or accidental sampling
• The sampling procedure for obtaining the people
  or units that are most conveniently available

5
Judgment Sampling

• An experienced individual selects the sample
  based on his or her judgment Representative of
  the population of interest.

6
Quota Sampling

• Two Step Process
• Develop some control characteristics
• Age
• Sex
• Race
• Sample is based on convenience or judgment.
• Characteristics same as target market

7
Snowball Sampling

• A variety of procedures
• Initial respondents are selected by probability
  methods
• Additional respondents are obtained from
  information provided by the initial respondents

8
Probability Sampling
Selected objectively, not at the whims of the
researcher

• Simple random sample
• Systematic sample
• Stratified sample

9
Simple Random Sampling

• A sampling procedure that ensures that each
  element in the population will have an equal
  chance of being included in the sample

10
Systematic Sampling

• A simple process
• Every nth name from the list will be drawn

11
Stratified Sampling

• Sub-samples are drawn within different strata
• Each stratum is more or less equal on some
  characteristic
• Not to be confuse with a quota sample