What is the main purpose of applying weights to sample estimates?

• A. Weights adjust for sampling design and nonresponse to improve representativeness.
• B. Weights increase the sample size.
• C. Weights reduce data collection cost.
• D. Weights directly improve data accuracy by fixing measurement errors.

Answer: (A)

Weights are used to make survey estimates reflect the population by correcting for unequal chances of selection and varying response rates. When some groups are more likely to be chosen or to respond, the unweighted average can be biased toward those groups. Applying weights assigns each observation a value that accounts for its probability of selection and response, so the weighted totals align with known population totals or distributions. This adjustment, often implemented through post-stratification or raking, improves representativeness across the population. Weights don’t increase the actual sample size, reduce data collection costs, or fix measurement errors, though they can affect variance and should be incorporated into standard errors to reflect the survey design.