Which of the following describes a standard element of a sampling plan?

• A. Specify sampling locations and timing
• B. Ignore QA/QC
• C. Record only what workers say
• D. Do not calibrate instruments

Answer: (A)

Focusing on where and when to collect samples is essential for any structured sampling plan. Defining sampling locations and timing provides the backbone for representativeness and comparability. By choosing specific places, you capture the spatial variability of the environment, and by scheduling when you sample, you capture temporal changes and events that could affect results. This clarity also supports logistics, ensures samples are collected within appropriate time windows to preserve integrity, and makes the data defendable in quality assessments.

In practice, a robust sampling plan includes this information so results can be interpreted reliably, trends can be tracked, and future sampling can be replicated under similar conditions. Without clear locations and timing, samples may be biased, inconsistent, or impossible to compare across sites or times.

Other options miss essential aspects of data quality and measurement: overlooking QA/QC leaves the data vulnerable to undetected errors; recording only what workers say ignores objective measurements and verifiable data; and not calibrating instruments risks inaccurate results due to drift or bias.