In analytical measurements, what does 'repeatability' refer to?

Repeatability in analytical measurements specifically refers to the consistency of results when the same method is applied to identical samples under the same conditions, including the same operator, equipment, and time. It assesses the precision of the measurement system by determining how similar results are when the same experiment is repeated.

This is crucial in analytical chemistry as it provides insight into the reliability of the measurements taken. High repeatability indicates that the method yields stable and reproducible results, which is essential for validating experimental findings and ensuring that any observed effects or concentrations are true reflections of the samples being analyzed, rather than errors or variability introduced by the measurement process itself.

The other options address different aspects of measurement validity but do not accurately define repeatability. The variation of results from different samples relates more closely to sample heterogeneity or method robustness rather than repeatability. The accuracy of results across different conditions pertains to reproducibility, which looks at consistency across varying settings. The average of multiple results from the same sample is a statistical method for data analysis but does not in itself convey anything about consistency or repeatability.