Algebra 2 · Unit 12 · Topic 12.3
Sampling, Bias, and Study Design
A sample describes a subset of a population, and selection methods influence whether it represents that population.
Definition and explanation
A sample describes a subset of a population, and selection methods influence whether it represents that population. Random sampling supports population inference; random assignment in an experiment addresses treatment-group comparability and is a different process.
Worked example
To study commute times at a school, sampling only students in an early bus queue can miss walkers and later arrivals. Randomly selecting students from the enrollment list addresses that selection problem more directly, though nonresponse can still introduce bias.
Common mistake
A large convenience sample can remain biased, and a survey association alone does not establish causation.
Key takeaway
A sample describes a subset of a population, and selection methods influence whether it represents that population.
Explain each step of the worked example, then check the units, signs, and conditions that apply.
Further reading
Topic coverage was checked against the openly available OpenStax Intermediate Algebra 2e, Algebra and Trigonometry 2e, and Introductory Statistics 2e textbooks. The explanations and examples on this site are independently written; textbook prose, exercises, and artwork are not reproduced.