Sampling Bias Math Example 3
Follow the full solution, then compare it with the other examples linked below.
Example 3
easyA school wants to know students' favorite lunch option. They survey only students in the cafeteria at noon. Identify the bias and suggest a better sampling method.
Solution
- 1 Bias: only students who eat cafeteria lunch are surveyed — students who bring lunch from home are systematically excluded
- 2 This is convenience sampling (only surveying those present in one location)
- 3 Better method: simple random sample from the school roster — randomly select students regardless of lunch habits
Answer
Convenience sampling bias excludes non-cafeteria students. Fix with simple random sampling from all students.
Convenience samples are fast and easy but often biased. The group available for easy sampling may not represent the full population. Random selection from the complete population is the gold standard for representative samples.
About Sampling Bias
Sampling bias occurs when the method of selecting a sample systematically over- or under-represents certain groups relative to their actual proportion in the population.
Learn more about Sampling Bias →More Sampling Bias Examples
Example 1 medium
A magazine surveys its readers about political preferences and finds 75% support Policy X. Explain w
Example 2 hardA researcher studies income by sampling shopping mall visitors on weekday afternoons. Identify at le
Example 4 hardAn online survey about internet usage gets 10,000 responses. Explain why this large sample does not