James Thomas' blog
Updated: 14 hours 36 min ago
Jerry Weinberg's definition of quality is well known. It is generally applied to encapsulate a relationship between a person and a product, at a particular time, and goes like this:
Quality is value to some personIt is intended to be a practical tool, and I think Weinberg would agree with something like this as a gloss for it: theoretical assessments of quality — perceived quality — are less important than those which are motivated by action. For example, a property is worth what someone actually pays for it. Without the action, it's just philosophy. What someone is willing to pay, or sacrifice, determines the quality (to them) at that moment.
I've thought about this definition a lot over the years. In particular I've found myself speculating about the granularity of the definition. Back in 2012 I was wondering whether it was interesting to consider quality in terms of the aggregation of a set of qualities; more recently I was thinking about the way that product quality and its effect on quality of life might be interesting; and just now I've been worrying away at the possibility of holding conflicting views of the quality of a product at the same time.
Although there are numerous examples in Weinberg's work of multiple people with differing opinions of a product at once, I haven't found any where a single person has that. Here's one relevant extract, from Quality Software Management volume 1, page 5:
For different persons, the same product will generally have different "quality," as in the case of my niece's word processor. My [complaint about a bug not being fixed] is resolved once I recognize that to [my niece], the people involved were her readers; and to [the word processor developer], the people involved were the majority of his customers.One of the things I find intriguing is that the definition, and its common usage, together seem to suggest that a person is only able to assert or demonstrate or alter their assessment of the quality of a product at certain times: when they pay for the product, and when they are making use of the product. So I tried some thought experiments.
In the first, I imagined that I might be in a position to buy a Bentley:
- I believe that the build standards of a Bentley are much higher than cheaper cars. I will pay more for higher build standard. This is a measure of value. As quality is value, I think the car is high quality.
- I believe I would get no extra benefit from a Bentley over some other cheaper car, given how I use my car. So I won't pay a high price for a Bentley. This is a measure of value. As quality is value, I think the car is low quality.
And then I reflected:
- I feel that I can hold these kinds of opposing views at the same time without problem (at least in some cases).
- I speculate that quality can be a relationship between a person and product-attribute rather than a product.
- My examples are couched in terms of belief rather than actual knowledge (I have never even sat in a Bentley)
- ... so to Weinberg I've really I've got a statement about perceived value, if anything, here.
- Perhaps related, quality assessment of wants (I'd love a Bentley) could be different to needs (I have to have some personal transport).
- Is there always, ultimately, some overriding single attribute of quality that wins out for any given person, at a given time, and so multiple perceived qualities collapse at the point of use into a single assessment?
- Or perhaps simultaneity is a false perception here. Maybe I am switching between views — very rapidly — and only hold one at any given time.
- Another angle: when I consider two contexts of use, or aspects, or applications of a product, could really be considering effectively two different products?
I tried another scenario, which attempts to take belief and perception out of the equation by using a more mundane product that I have personal experience of. Let's say I have bought a new pen and I want to use it for two tasks: taking notes while standing up and taking notes while suspended by my feet.
- The pen is suitable for the first task and I am very happy with the price I paid. I say this is a good quality pen.
- The pen is not suitable for the second task. I had to keep inverting it to let ink run back to the nib end, which I am unwilling to do any longer. I say this is a low quality pen.
- At the point where I pay for my pen, by Weinberg's model, I make an explicit statement about the quality of the pen for me.
- Unintuitively, perhaps, if I've never used such a pen before this is based only on my perception of the value the pen will return to me
- ... so perceived quality can turn into actual quality with no additional evidence to back it up
- ... and, on engagement with the pen, I might rapidly revise my opinion.
- Once I've paid for it, I express my view of the quality of the pen by the extent to which I am prepared to sacrifice to use it
- ... and (if I understand the model) effectively the only time at which I can express this view is at the point of use
- ... because at other times I merely express a perception of what I would do when I came to use it
- ... and so can I change my expression of the quality of the pen without using it?
- For example, can I express an opinion on quality by choosing not to use something?
- ... but then how to distinguish between something that I happen not to use and something that I actively don't use, and something that I use only occasionally but is perfect for a particular task?
And then I stopped and dumped my notes here, after pondering how much I was prepared to sacrifice to continue this particular line of thought at this time.
With thanks to Jerry for patiently listening to me trying to make some kind of argument along these lines in email, and then patiently declining to agree. And also to Šime for prompting more thoughts when I was going round in circles.
Categories: Software Testing