Importance of knowing the nature of the purpose and the population of your study
a) Simple Random:
• Each subject is chosen by chance and all subjects have equal likelihood of being chosen.
• All sub-groups have equal probability of being chosen.
• The population is divided into groups (called stratas) based off characteristics, and then random subjects are chosen from each strata.
• A non-random sample.
• Formed by subjects who are easy to reach (convenient to reach).
• The population is first divided into randomly chosen sub-groups (called clusters), then a random assortment of these clusters are chosen to be the sample.
• The population is first formed into an exhaustive list, and then every
member is chosen to be part of the sample.