stratified

• 1. sophisticated form of sampling . From a wider population a subgroup is created (strata) based on age etc. Population is randomly sampled within each strata
• strength

  • Avoid researcher bias → participants are randomly selected
  • Method produces a representative sample
• weakness:

  • Requires detailed knowledge of population characteristics : which may not be available
  • Very time-consuming dividing a sample into strata and then randomly selecting from each