Sympathetic Vibratory Physics

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. [from https://www.labmate-online.com/news/news-and-views/5/breaking-news/what-is-the-difference-between-Repeatability-and-Reproducibility/30638]

Repeatability and Reproducibility are the two components of precision in a measurement system.

Repeatability and Reproducibility are factors in Uncertainty Calculations of measurements.

Repeatability

Repeatability is the closeness of measured values between repeated measurements of the same thing, carried out at the same conditions as follows.

At the same place
By the same person
By the same Method
On the same equipment
Over short period of time.

In simple words, Repeatability is variation in readings when the same person measures the same part many times using the same equipment and method under the same conditions.

Example

If a person measures repeated readings of an object by micrometer as 15.01 mm, 15.02 mm, and 15.01 mm. means the person can repeat the readings, and the level of competence is high.

Repeatability is calculated by standard deviation of readings.

Why Repeatability is Important?

If the same person repeats the readings within the accuracy of the instrument, then that person is competent.

We can check the level of competence of a person by checking the Repeatability of readings.

If a person cannot repeat readings, proper training is given.

If equipment is not repeating readings even if readings are taken by competence person, then instruments is due for servicing (repairing).

Reproducibility

Reproducibility is the closeness of measured values between measurements of the same thing carried out in different conditions as follows

At the different place
By the different person
By the different method
On the different equipment
At the different time

In simple words, Reproducibility is the variation in readings when a different person measures the same part (or quantity) many times, using the same equipment (or different equipment), under the same conditions (or different Conditions).

Example

If three different person measures reading of the same object by micrometer as 15.54 mm,15.64 mm,15.49 mm, then the Reproducibility of this measurement is 0.15 mm.

There are many different ways (formulas) to calculate Reproducibility.
Why Reproducibility is Important?

Reproducibility is important because it demonstrates that the lab has the ability to replicate measurement results under various conditions.

If the lab conducts a Reproducibility test evaluating every technician and one technician’s readings were significantly different from all others, the lab should provide proper training to improve his skills and increase his level of competence.

It helps to monitor the quality of work.

Inter-laboratory Comparison (ILC)

Inter-laboratory comparison (ILC) is the comparison of results between two or more labs.

I.e. Reproducibility of results between two or more calibration labs.

Inter-laboratory comparison (ILC) is to check the competence of lab by comparing their results, whether they can reproduce similar results as other labs.

ILC improves the reliability of results.

Differences

A Significant difference in Repeatability and Reproducibility can indicate following problems:

A place may introduce additional error (e.g. Vibrating surface while calibration of weights)
Lack of Skill of Operator
A method may be inappropriate
Equipment is Faulty
Environment condition is unstable (e.g. Temperature is an important parameter in dimensional metrology)

Author: Saurabh Vaidya https://instrumentationtools.com/difference-between-Repeatability-and-Reproducibility/

Replication Reproduction (and Replicability) versus Reproduction (and Reproducibility)

Some scientists use the term replication (and replicability) as synonyms of reproduction (and Reproducibility).

For example, Shuttleworth (2009) writes that Reproducibility is regarded as one of the foundations of the entire scientific method, a benchmark upon which the reliability of an experiment can be tested. The basic principle is that, for any research program, an independent researcher should be able to replicate the experiment, under the same conditions, and achieve the same results.

However, some scientists distinguish between replication (and replicability) versus reproduction (and Reproducibility).

For example, Peng (2011) defines replication as [a group of independent] researchers going out and collecting new data in an attempt to replicate a study previously conducted by another group of researchers. In contrast, Peng defines Reproducibility as [a group of independent] researchers analyzing the [previously collected] data of a study previously conducted by another group of researchers.

So, according to Peng (2011), with replication, an independent group of researchers conduct a replication of a previously conducted study, including collecting and analyzing their own data, to see if they get the same results; with reproduction, an independent group of researchers analyze the data from a previously conducted study to see if they get the same results.

In addition, Shuttleworth (2009) distinguishes between Reproducibility and Repeatability, which is when the (same) researchers repeat their (own) experiment to test and verify their results. https://online225.psych.wisc.edu/wp-content/uploads/225-Master/225-UnitPages/Unit-04/Replication_vs_Reproduction.pdf

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Repeatability and Reproducibility