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Validation before Verification. Why not?

SSchoepel

Involved In Discussions
#1
I'm reading 21CFR820, ISO13485, and ISO14969 to clarify for the company the difference between verification and validation.

My question may apply to other medical devices but for a software-only (no hardware at all) medical device, it seems possible, plausible, and defensible to have validation prior to verification.

Alpha software could be tested against use cases and sent to customers to validate the flow/features. Then, the development could finish and all the internal requirements verified. If there were changes in the use cases between the alpha validation version and the final verified version, you could validate just the delta. If there were no changes, no validation.

Has anyone done this and had it pass certification/audit?
Or has everyone just fallen out of their chairs?

Thank you,
S. Schoepel
 

John Broomfield

Staff member
Super Moderator
#2
I'm reading 21CFR820, ISO13485, and ISO14969 to clarify for the company the difference between verification and validation.

My question may apply to other medical devices but for a software-only (no hardware at all) medical device, it seems possible, plausible, and defensible to have validation prior to verification.

Alpha software could be tested against use cases and sent to customers to validate the flow/features. Then, the development could finish and all the internal requirements verified. If there were changes in the use cases between the alpha validation version and the final verified version, you could validate just the delta. If there were no changes, no validation.

Has anyone done this and had it pass certification/audit?
Or has everyone just fallen out of their chairs?

Thank you,
S. Schoepel
If you validate before you verify you do not know exactly what you validated.
 
G

Guillaume Prom

#3
verification and validation are defined in ISO9000.

usually for medical device verification is done before validation, in order to verify that the device is safe before using it under real conditions.

"If there were no changes, no validation" it doesn't shock me.. but there is always changes ;-)
 
P

pldey42

#4
In my experience of real time telecom software, verification involves inspections of designs and code against formal requirements, perhaps coupled with module and lab testing, while validation is large scale testing of complete systems, possibly under controlled conditions in the field.

So validation is more expensive; verification can discover defects earlier and more cheaply. Further, verification can discover defects that are hard to impossible to detect with tests - such as memory allocation-de-allocation mismatches - that can have catastrophic consequences for real time systems that must operate 24/7.

Also, validating just deltas could be risky because it can miss defects that have been introduced by the delta: for example, a new feature works but breaks something that previously worked, but, not being noted in the delta, isn't tested again but is in fact broken.
 
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