Old Favourite: QA / Testing – what’s the difference?

Software is about the only industry one of the few industries that lumps testing and QA under one banner. It’s one of those things where common misuse of a term results in the community changing it’s meaning… this happens in mainstream language all the time.

Testing something is actually more analogous to quality control or, QC , [although it isn’t quality control].

QA is more concerned with the process – collecting information about the performance of the process in order to determine if we are ‘assuring’ (or more realistically increasing the probability of) quality. Statistical information about problems found in the product (during quality control) is just one of many pieces of info useful to someone concerned with QA (which really should be the whole project team)

In short:

QC helps us answer the question ‘does our product work?’

QA helps us answer the question ‘does our process work?’

Unfortunately, in the software industry, all too many teams don’t realise their process doesn’t work until the testers find all the ways in which the product doesn’t work… maybe that’s why software testing has come to be known as QA.

This article originally appeared on my old blog in July 2008. I had already elaborated on this topic in the article “What’s in a word” in Better Software Magazine in March 2008.

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  • There’s been a subtle evolution to how I express my thinking on this subject since I wrote these articles in 2008. ..

    Although “Testing” is more analogous to “Quality Control” it isn’t “Quality Control”.

    Quality Controllers have the ability to reject or accept a product based on a set of pre-set criteria (and perhaps a certain amount of their own judgement).

    In software teams, in my experience, this is rarely a decision made by the person(s) testing it… and rightly so.

    It is a decision made by the ‘product owner’ or ‘product manager’, or others with more visibility of the business concerns.

    We are ‘developing’ a product – not manufacturing one. Something being wrong with our product is analogous to something being wrong with the design or entire production line of a manufactured product – i.e. all instances of that product will be affected, not just one at the end of the production line.

    All affected stakeholders should have some influence on the decision and it should be decided based on a risk vs. reward basis (relevant to that the business or domain). Testers can tell the business folks what the deficiencies of the product are but the people with their finger on the pulse of the business and its market are best placed to decide whether going live is a risk worth taking.

    So, the only variation I would add to the above is to emphasise the word “more” in the statement “Testing is more analogous to Quality Control.” And I’d say “but Testing is not Quality Control”.