What is the Difference Between Repeatability and
Reproducibility?
Repeatability and reproducibility are ways of measuring
precision, particularly in the fields of chemistry and engineering. In general,
scientists perform the same experiment several times in order to confirm their
findings. These findings may show variation. In the context of an
experiment, repeatability measures the
variation in measurements taken by a single instrument or person under the same
conditions, while reproducibility measures whether an entire study or
experiment can be reproduced in its entirety.
Within scientific write ups, reproducibility and
repeatability are often reported as standard deviation. The article From Crude
Mixture to Pure Compound – Automatic Purification Made Easy discusses how
scientists and researchers establish repeatability and reproducibility in more
detail.
What is repeatability?
Repeatability practices were introduced by scientists Bland
and Altman. For repeatability to be established, the following conditions must
be in place: the same location; the same measurement procedure; the same
observer; the same measuring instrument, used under the same conditions; and
repetition over a short period of time.
What’s known as “the repeatability coefficient” is a
measurement of precision, which denotes the absolute difference between a pair
of repeated test results.
What is reproducibility?
Reproducibility, on the other hand, refers to the degree of
agreement between the results of experiments conducted by different
individuals, at different locations, with different instruments. Put simply, it
measures our ability to replicate the findings of others. Through their
extensive research, controlled inter-laboratory test programs are able to
determine reproducibility. The article Precise Low Temperature Control Improves
Reaction Reproducibility discusses the challenges related to reproducibility in
more detail.
Why are repeatability and reproducibility considered
desirable?
In terms of repeatability and reproducibility, test/re-test
reliability demonstrates that scientific findings and constructs are not
expected to alter over time. For instance, if you used a certain method to
measure the length of an adult’s arm, and then repeated the process two years later
using the same method, it’s highly likely that your results would correlate.
Yet if your results differed greatly, you would probably conclude that your
findings were inaccurate, leading you on to further investigations. As such,
repeatability and reliability imbue investigative findings with a degree of
authority.
We can also use
repeatability and reliability to measure difference and a lack of correlation.
If, for instance, we are unable to repeat or reproduce our findings, we have to
ask ourselves why, and to investigate further.
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