Sampling Bias Statistics Example 2
Follow the full solution, then compare it with the other examples linked below.
Example 2
mediumA website runs an online poll asking 'Should the government raise taxes?' and 90% of respondents say 'No'. Can this result be trusted? Explain what type of bias is present.
Solution
- 1 Step 1: This is a voluntary response sample — only people who choose to participate respond, which means those with strong opinions are over-represented.
- 2 Step 2: People who feel strongly against tax increases are more likely to seek out and respond to such a poll, while those who are neutral or mildly in favour may not bother.
- 3 Step 3: Additionally, the sample is limited to people who visit that specific website, introducing further selection bias. The result cannot be generalised to the broader population.
Answer
The result cannot be trusted due to voluntary response bias — people with strong negative opinions about taxes are more likely to respond, skewing the result.
Voluntary response bias occurs when participants self-select into a survey, typically because they feel strongly about the topic. This systematically excludes moderate opinions and produces results that exaggerate extreme viewpoints.
About Sampling Bias
Sampling bias occurs when a sample is collected in a way that systematically makes some members of the population more likely to be included than others, producing results that do not accurately represent the full population and leading to misleading conclusions.
Learn more about Sampling Bias →More Sampling Bias Examples
Example 1 easy
A school wants to know whether students prefer longer lunch breaks. They survey students in the cafe
Example 3 mediumA researcher wants to estimate the average income of adults in a city. She interviews people at a sh
Example 4 hardIn the 1936 US presidential election, the Literary Digest magazine polled 2.4 million people and pre