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voluntary response

people with stronger opinions or interests are more likely to participate in surveys or studies, leading to biased results.

convenience sampling

choosing the easiest people to reach (social media, email, etc)

undercoverage

some groups are left out of the process of choosing the sample

selection bias

a group has little to no chance of being selected and favors certain outcomes

representative sample

has same properties and breakdowns as the population

simple random sample

ensures every group of a fixed size has the same chance of being included in the sample

simple random sample

random # generator draws random sample and ignores repeats (sampling without replacement)

stratified random sample

divides population in groups based on similarities and takes random sample from each

stratified random sample

equal representation and diversity

cluster sampling

dividing into random clusters and random selection of clusters is made to survey; meant for larger and spread out populations, cheaper and saves time

systematic sampling

“every 10th person survey”

randomized response sampling

sensitive questions answered randomly to encourage honest responses anonymously