Which attribute describes the consistency of test results when the same sample is analyzed multiple times under identical conditions?

• A. Repeatability
• B. Means of reporting
• C. Clean bottles
• D. Quality control results

Answer: (A)

Repeatability is the degree to which test results are nearly the same when the same sample is measured multiple times under identical conditions. It reflects precision under fixed conditions: same method, same instrument, same operator, and a short time frame. If repeated analyses of the same sample yield values that cluster tightly, the test has high repeatability, indicating low random error and stable performance. In wastewater testing, this means the method produces consistent results from one measurement to the next, which is essential for reliable data. If the results vary widely on repeated trials, repeatability is low, signaling possible issues with the equipment, technique, or sample handling.