Sampling Bias
Definition
When the sample is not representative of the population.
Example
A researcher wishes to understand the relationship between socioeconomic status and mental health status in the United States. The participants for the study are drawn from one zip code near the research facility.
Why It Matters
Sampling bias can seriously weaken a study’s results. If the sample doesn’t reflect the larger population, the findings may not apply beyond the people who were studied. Being aware of sampling bias helps researchers choose participants more carefully and draw conclusions that are actually useful.