Statistical sampling is used when which condition applies?

• A. Background information is available
• B. No background information available
• C. Contamination signs are evident
• D. Extensive preliminary data exists

Answer: (B)

When there is no reliable background information about the population, you use statistical sampling to learn about it. By taking a representative subset and analyzing it, you can estimate population characteristics (like the average value or proportion) and attach a quantified uncertainty to those estimates. This approach is efficient when testing every item is impractical or unnecessary, yet you still need to make informed conclusions about the whole group. If background information is available, decisions can often rely on that data or on targeted testing rather than broad sampling. Contamination signs show what to look for, but they don’t determine the need for sampling. Likewise, having extensive preliminary data can guide the sampling plan, but the fundamental reason to sample is the lack of prior information about the population.