Sampling Bias Math Example 1
Follow the full solution, then compare it with the other examples linked below.
Example 1
mediumA magazine surveys its readers about political preferences and finds 75% support Policy X. Explain why this result may not represent the general population, identifying the bias type.
Solution
- 1 The sample is magazine readers — a self-selected, non-representative group
- 2 Magazine readers tend to share demographics (age, education, interests) that may align with specific political views
- 3 Bias type: voluntary response bias (readers choose to subscribe) + convenience sampling (easiest to survey own readers)
- 4 The sample systematically excludes non-readers who may have different political views
Answer
Voluntary response and convenience bias make readers non-representative of the general population.
Sampling bias occurs when the sample systematically over- or under-represents certain groups. Literary Digest's 1936 poll (from car owners and phone subscribers) famously predicted the wrong winner for this reason. Representative sampling requires random selection from the target population.
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 2 hard
A researcher studies income by sampling shopping mall visitors on weekday afternoons. Identify at le
Example 3 easyA school wants to know students' favorite lunch option. They survey only students in the cafeteria a
Example 4 hardAn online survey about internet usage gets 10,000 responses. Explain why this large sample does not