This document discusses different methods for collecting data and sampling techniques. It describes common data collection methods like surveys, questionnaires, and interviews. For sampling, it explains random sampling which uses chance to select subjects, systematic sampling which selects every kth subject, stratified sampling which divides a population into groups and samples from each, and cluster sampling which divides a population into clusters and randomly selects some clusters.

1. Data Collection
and Sampling
Techniques

2. Data Collection
• Telephone surveys
• Mailed questionnaire
• Personal interview surveys
• Surveying Records or direct observation of
situations

3. Sampling Techniques
• Random Sampling
• Systematic Sampling
• Stratified Sampling
• Cluster Sampling
• Other Sampling Methods

4. Random Sampling
• Random samples are selected by using
chance methods or random numbers.
■ One such method is to number each subject
in the population. Then place numbered cards
in a bowl, mix them thoroughly, and select as
many cards as needed. The subjects whose
numbers are selected constitute the sample.
■ Random number generator

5. Systematic Sampling
• Researchers obtain systematic samples by
numbering each subject of the population
and then selecting every kth subject.
■ For example, suppose there were 2000
subjects in the population and a sample of
50 subjects were needed. Since 2000 50
40, then k=40
■ First number from 1-40 would be selected
randomly

6. Systematic Sampling
• Researchers obtain systematic samples by
numbering each subject of the population
and then selecting every kth subject.
■ For example, suppose there were 2000
subjects in the population and a sample of
50 subjects were needed. Since 2000 50
40, then k=40
■ First number from 1-40 would be selected
randomly

7. Systematic Sampling

8. Stratefied Sampling
• Researchers obtain stratified samples by
dividing the population into groups (called
strata) according to some characteristic that
is important to the study, then sampling from
each group.

9. Cluster Sampling
• Here the population is divided into groups
called clusters by some means such as
geographic area or schools in a large school
district, etc.
• Then the researcher randomly selects some
of these clusters and uses all members of the
• selected clusters as the subjects of the
samples.

10. Sampling Techniques
• Random Sampling
• Systematic Sampling
• Stratified Sampling
• Cluster Sampling
• Other Sampling Methods