U3U4 - Sampling techniques Flashcards
population vs. sample
Population
All individuals who belong to a group being studied, ex. A whole class, whole school, whole city.
Sample
Is used when the population is too large or difficult to survey in its entirety so a smaller group is surveyed.
When a population is too difficult to survey in its entirety, we must choose the most appropriate sampling technique to ensure the most accurate results.
systematic sample
Systematic sample - where you have to order the population by age, size, etc and sequentially select members at regular intervals where interval size = population size/sample size.
.
random sample
Types of sampling techniques:
Random sample - where every member of the population has an equal chance of getting selected.
Ex. randomly picking 5 students of 30 by pulling names out of a hat.
stratified sample
Stratified sample - divide the population into groups with similarities and then an equal percentage is randomly selected from each of those groups.
cluster sample
Cluster sample - the population is separated into different groups by location and one or more of these groups are randomly selected.
Ex. a school board could survey its students by randomly selecting 5 schools in the board instead of all schools.
multi stage sample
Multi stage sample - a random sample of a population is taken, then another random sample is taken from that sample and so on.
Ex. Canada chooses a random province to survey, then a random city in that province, then a random neighbourhood in that city and so on.
voluntary response sample
Voluntary response sample - the entire population is invited to participate.
Voting for American Idol or a Federal Election
convenience sample
Convenience sample - the respondent participates because the survey is easily accessible. Ex. surveys on receipts or pop up surveys from online
