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The words "validation" and "verification" frequently appear when reading the results of a paper. A Google search of these words left me even more confused:

verification: The process of establishing the truth, accuracy, or validity of something.

validation: The action of checking or proving the validity or accuracy of something.

Example: I constructed a mathematical model of real-world system. I compared the model results with actual values and found that the model had an acceptable error.
Did I verify or validate my model?

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    $\begingroup$ This will vary by field. In software, for example, these are well-defined: verification means "are we building the product right?", whereas validation is "are we building the right product?". $\endgroup$
    – cag51
    Sep 22, 2019 at 18:44
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    $\begingroup$ I like this variant (source forgotten): verification means “are the equations evaluated correctly?” while validation means “are the correct equations evaluated?”. $\endgroup$
    – Ed V
    Sep 22, 2019 at 19:04
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    $\begingroup$ @cag51 That use isn't just for software, but for product quality management in general. I guess it works in computer simulation models terminology, provided "right product" is interpreted as a model matching reality. $\endgroup$
    – Anyon
    Sep 22, 2019 at 19:06
  • $\begingroup$ You can also look at asme.org/codes-standards/publications-information/… $\endgroup$
    – Biswajit Banerjee
    Sep 23, 2019 at 19:37

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Here's an illustration to explain the difference. Suppose you were creating an accounting system for Enron, before it collapsed. The specification said you need to ensure that the output assumed that 2+2=5.

Verification is asking the system "what is 2 + 2" and getting the answer "5".

Validation is discovering that the Securities and Exchange Commission thought the correct answer should have been "4".

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Validation: Are we building the right product?

Verification: Are we building the product right?

Validation is the process of making sure that you have objective evidence that user needs and intended uses are met. ... Verification is typically making sure that you have objective evidence that specified requirements are met. It is usually done by tests, inspections, and in some cases analysis as well.

i.e. when you are designing something, you will write a series of requirements relating to user needs. Validation is the check that those requirements actually meet the users needs, and then Verification is the check that you've actually met the requirements that you set out for yourself.

For example, a requirement might be "This device must be light enough for all users to pick up".

You might then write a reqirement, such as "The device must weigh < 30kg"

You could Validate this, to show that your specified requirement actually meets the user need by doing research to find out how much weight your users could acutally lift, or by referencing some existing research if the grip etc. is comparable. There will of course be other requirements (e.g. size, grip features), that also need to be included in order to ensure that the user need is met.

Once you've manufactured your device, you then Verify that it meets your requirements, by performing a physical test - weigh the device, and check that against your specification.

In some cases, certain features e.g. "the device must be <1m long" can be verified through a technical report (e.g. drawing review) without the need for a physical test. In this case e.g. if the device is supplied with a Certificate of Conformity confirming that it matches the drawings.

In the example that you wrote, you are performing a real world test, and then comparing this information to a value that was set by your previous research would be Verification

Checking whether or not your mathematical model actually shows you something useful with regard to a user need would be Validation.

Source: ASME https://www.asme.org/topics-resources/content/validation-verification-for-medical-devices

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You likely did both, but with different processes. You create a mathematical or computer model and you check that it matches the ideas that underlie it. In a computer model you check that you haven't made mistakes in the programming. In a mathematical model you check that you have used the right equations (or whatever) and evaluated them correctly. This is verification. I verify that the model is what I say it is.

The other part requires matching the output of the model to some "real world" values. This is validation. But it is actually only partial validation since the world isn't a deterministic machine and a different set of values from the world or a different "run" of the model might give wildly different values.

Often validation of an experiment means that some one, usually someone else, has used a different experiment and come to the same conclusion. "Yes, several studies show that children are shorter than adults." This is validation by replication, but not necessarily using exactly the same experimental design.

Verification of a design is a process to determine that the design can be expected to give valid results. A study that just "guessed" at the heights of people would be hard to verify.

Presumably you did both. You verified the design. You validated the results.

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  • $\begingroup$ Hi Buffy, your answer was very helpful. I, however, would like to delete my question and add it to scicomp.stackexchange as I thought it would be more relevant. Would you mind deleting your answer and posting it to scicomp again? $\endgroup$
    – Neil
    Sep 23, 2019 at 6:01
  • $\begingroup$ I will ask the moderators to migrate it. Migrating will leave a trace here so that it can be found there. $\endgroup$
    – Buffy
    Sep 23, 2019 at 11:17
  • $\begingroup$ Actually cross posting is strongly frowned upon here. Suggest you delete the other one and flag this one for moderator attention. $\endgroup$
    – Buffy
    Sep 23, 2019 at 12:46
  • $\begingroup$ I deleted the other one and flagged this one for moderation. $\endgroup$
    – Neil
    Sep 23, 2019 at 12:49

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