Quality: different purposes, different definitions

For years when asked to define quality, I’ve said “value to a person who matters”1. Not too long ago I used that definition in the first post of my four-part series “Thinking about quality”. However, in the fourth post of that series I also said that quality is something emergent. And I continued with:

We can have long discussions about what quality is, but that’s a different question from how do you get quality?

Today I took this one step further, when I realized that depending on the context, I talk very differently about quality. And while I may not define ‘quality’ explicitly in every conversation, implicitly I’m still using different definitions. That alone, I think is interesting: instead of a single, general definition of quality that always applies, I have different definitions depending on their purpose2.

When I talk about testing, I do think of quality as “value to someone who matters”. When I talk about software development, however, I think of quality as “many small things done right”3.

The reason for this difference is that these definitions serve different purposes. When I’m testing, I’m assessing quality. So I need a definition that helps me to decide what quality is. When my concern is software development, I need a definition that helps me to decide how to deliver quality. And if I were a manager, I’d need a third definition of quality. And if my focus would be running a successful business, I’d need yet another one. And so on.

In general, I think this is a good question to ask of any definition (or model): what kinds of decisions does this definition allow you to make?

  1. This is James Bach’s definition, extending Jerry Weinberg’s “value to some person”. 

  2. I would even go one step further than that and following Ludwig Wittgenstein’s PI 34 “For a large class of cases of the employment of the word ‘meaning’ - though not for all - this word can be explained in this way: the meaning of a word is its use in language.” claim that a definition is a “use of language” like many others and not a special usage granting meaning to a word. 

  3. Borrowed from Marco Pierre White’s definition of perfection.