Which is an advantage of stratified sampling?

• A. Avoids bias
• B. Access may be a problem
• C. Requires good prior knowledge
• D. Difficult to know which subsets to include

Answer: (A)

Dividing the population into subgroups (strata) that share a common characteristic and then sampling from each one helps ensure every important subgroup is represented in the final sample. That representation reduces the risk that the overall results are biased toward one part of the population, which makes the estimates more accurate.

So, the advantage is that stratified sampling helps avoid bias by guaranteeing inclusion of each subgroup’s views or values, rather than letting some groups be under- or over-represented by chance.

In practical terms, some challenges you might encounter include that access to all strata can be difficult, and you need good knowledge to define meaningful strata or decide which subsets to include. Those are obstacles, not advantages.