Sampling and sampling techniques

• Population


  Refers to the an entire group that is under the study or investigation
• Parameters


  Measurements that describe the population
• Sample


  A subset taken of population. A sample is a representation of the population with which one hopes to draw a valid conclusion
• Statistic


  Measurements that describe the sample
• Sampling


  The process or technique of selecting a representative sample from the entire population to achieve unbiased results
• Types of Sampling


  • Probability sampling (random sampling)
  • Nonprobability sampling (non-random sampling)
• Probability sampling


  • The subjects of the population get an equal opportunity to be selected as a representative sample
• Nonprobability sampling


  • The sample is not a proportion of the population and there is no system for selecting a sample
• Types of Probability Sampling


  • Simple random sampling
  • Systematic Sampling
  • Stratified sampling
  • Cluster sampling (area sampling)
  • Multistage sampling
• Simple random sampling


  Every element of the population has an equal chance or probability of being selected for inclusions in the sample
• Systematic Sampling


  Every kth element of the population is selected until the desired number of elements in the sample is obtained
• Stratified sampling


  The population is divided into groups called strata, which is based on similar characteristics
• Cluster sampling (area sampling)


  The elements of the population are divided into groups called clusters. Usually, the clusters are based on naturally occurring clusters mainly geographical such as cities, barangays, or municipalities
• Multistage sampling


  A combination of different sampling techniques is done in selecting respondents
• Types of Nonprobability Sampling


  • Accidental Sampling
  • Convenience sampling
  • Snowball sampling
  • Quota sampling
  • Purposive sampling
• Accidental Sampling


  Only those whom the researcher meets by chance are included in the sample
• Convenience sampling


  People are sampled simply because they are "convenient" sources of data for researchers
• Snowball sampling


  Existing study subjects recruit future subjects from among their acquaintances
• Quota sampling


  You take a very tailored sample that's in proportion to some characteristic or trait of a population
• Purposive sampling


  The sample is defined for a purpose that is relevant to a specific study or research