Sampling Bias

Statistics · Axiom Academy

Understanding how bias can affect statistical sampling and how to avoid it A researcher studies college students' study habits by surveying only those in the library. This creates selection bias because students who don't use the library (but may study elsewhere) are excluded from the sample. Ensure all members of the population have an equal chance of selection Avoid convenience sampling (selecting whoever is easily accessible) A survey asks: "Don't you agree that exercise is important for health?" The leading question encourages respondents to answer "yes" regardless of their true beliefs, creating response bias. Use neutral, unbiased question wording Avoid leading or loaded questions Ensure anonymity to reduce social desirability bias Provide clear, unambiguous answer options A political poll is conducted via landline phones. Younger people, who rarely have landlines, are less likely to respond, creating non-response bias that skews results toward older demographics. How to Avoid Non-Response Bias Follow up with non-respondents multiple times Use multiple contact methods (phone, email, mail) Keep surveys short and convenient Provide incentives for participation Compare respondents to non-respondents when possible Example of Voluntary Response Bias

This is the written version of the interactive lesson above. See the full Statistics course.