Unit 2 Sampling Methods Flashcards
A strata
A group of people who are alike based on a characteristic. Used for sampling.
Stratified Sampling
Each strata gets its own hat. Randomly select people from every strata to survey.
A cluster
A mixed group of people that should be representative of the population
Cluster Sampling
Put the names of the clusters in the hat. Randomly select one or more clusters and survey some/all the people in those clusters only.
Systematic Sampling
Sample every nth person.
Simple Random Sample
Every person in the population goes in the hat. Randomly select from the hat. Every person has an equal chance of being chosen. Every group of people has an equal chance of being chosen.
Convenience Sample
Survey the people who are around you; who are convenient and easy to survey. A bad sampling method.
Response Bias
People give answers that don’t represent their true feelings:
- wording of the question is confusing
- question is about something embarassing or illegal
- intimidated by person asking the question
- wording of the question makes people feel like they should answer a certain way (leading question)
Voluntary Response Bias
No randomization in the selection. People self-select to answer the survey. Usually only people with strong opinions respond.
Non-Response Bias
The researcher randomly selects people to participate in the survey, but those people do not respond.
Undercoverage
The survey is done in a way that leaves out a certain segment of the population.
What is biased data?
Data that over-estimates or under-estimates the proportion of people in the population that feel a certain way.
Give examples of appropriate variables on which to stratify.
Age Race Gender Income Level Political Affiliation
Give examples of variables which are usually not appropriate to stratify.
Shoe size
Height
Length of Hair
Give examples of typical clusters
Neighborhoods, cities, or other geographic regions
Rooms, rows, or other locations in a building
