It seems to me that what people usually mean by a product’s “quality” is the overall value someone might gain from it, ignoring its price. Sometimes people talk about a product’s “value”, or it being a good “deal,” referring to its over all value including its price. And sometimes people will talk about quality given certain constraints. For example, folks might talk about a “great one bedroom apartment” suggesting that two bedroom place might be better, but that such comparisons are set aside for now. But the most common way to evaluate products is to just talk about value ignoring price. Yet why ignore price?
Quality is the inverse of the predictability of demand.
Quality is a parameter which signifies and evaluates the products features which make this beneficial for their consumers, degree of quality shows the authenticity and usability of products
Quality is related to the end for which something is made. Does it do what it was intended to do well.
Here's another suggested theory: The quality of a product is a measure of how well it fulfills its function, with its function determined, in large part, by the type of product that it is. One can hammer more nails, or more types of nails, or more nails over the course of a lifetime, with a high-quality hammer than with a low-quality one. High quality ladders are less likely to collapse or be unstable than low quality ones, high-quality massages are more likely to leave the buyer relaxed than low-quality massages, etc.
It would follow from this definition that judgements of quality would start to diverge just as soon as our opinions about what the purpose of some product or service is. Two people can agree that they want to give their son a "quality education" without thereby agreeing about what that means, because they disagree what the purpose of an education is, and thus what makes an education good or bad. And this seems to me exactly what we do find.
.What Is “Quality”?
This isn't my impression. I think statements such as "this netbook is built to be light and cheap, but it's low quality " or "this 17-inch monitor is smaller than most, of course, but it's high quality" are very common. Further, in support to James' theory, things like weight and screen size become part of quality when the product has many parts and those qualities become minor, e.g. "this boat is low quality; all the screens in the cockpit are tiny" or "this house is low-quality; all the doors are light and flimsy". But we wouldn't say the boat is low-quality because of it's length and we wouldn't say the house is low-quality because it's a 2-bedroom.
But we commonly explicitly describe certain properties, like weight or screen size, and then also include those things in "quality."
That is a plausible alternative to consider.
We can flip this around. What is "quantity?" It's not easy to talk about the nature of a good independent of many features. As economists say, A car that you can drive off the lot this second is not the same as one that will be delivered in 10 months. Quality does seem to be a catchall for those positive modifiers of quantity/value not capturable by sheer enumeration. So a bigger box of cookies isn't a higher quality than a smaller box of the same cookies.
On the other hand durability is tricky. If a TV is the same subjective quality as another (in terms of viewing) but lasts twice as long, we speak of its having higher quality.
Marketers say that Europeans focus more on the subjective experience of driving a car for evaluating quality while Americans tend to weigh reliability almost as highly as perceived subjective "feel" when speaking of quality.
Cultural / hard-wired taboos against market transactions make an explicit monetary price a novel idea.
Our ancestors grew up with reciprocal gift-giving, communal property, and authoritarian control. Market pricing is novel and generally not trusted. Pinker discusses this in some of his pop sci books.
People probably do implicitly include costs into their assessment of something...but what shows up on the surface is governed more by social considerations.
Simple: the price signal overwhelms the quality signal.
For example: in a blind taste test of wine, people who do not know the cost of each wine, still prefer the expensive wine to the cheap wine, but the spread is much less than if they are told before tasting how much each of the wines costs.
Unless you evaluate wines ignoring price, you can't know whether you like a wine more because of its intrinsic quality, or whether you like it more simply because it costs more.
The best definition of "quality" that I have seen is "how well the item or service fulfills its consumers needs."
The terms `good' quality and `quality control' have no meaningexcept with reference to the consumer's needs. W Edwards Deming
The third theory sounds most convincing to me.
I do have a Fourth Theory: Quality is used to measure the skill of the people who made the product, thus determining their personal merit. Price is not factored in because that measures the skill's scarcity, not its level.
If this theory was true then we would also judge skills other than making goods, irrespective of price. For instance, we would say "X is the best chef in the world" or "Y is the best musician in the world" without regard to how much it costs to buy a meal from X or attend a concert by Y. That does appear to be the case in the real world.
Generalizing on some of the earlier comments -
In cases where money isn't the only scarce resource (e.g. space or power might be additional ones), people tend to naturally break those out separately from quality in just the same way they routinely do with price.
Linear programming is one kind of systematic approach to certain problems of this type: In LP one tries to maximize an 'objective function' of a set of independent variables subject to a set of linear constraints on those variables. The constraints can represent available quantities, and usages, of scarce resources.
This is a fun and fruitful game: thinking of consequences of explicit theories explaining something that's obvious. Saying that separating quality and cost is obvious is obvious.
It's unfortunate when it happens the other way around, where 'price' affects social perceptions of quality. I think people are less fooled by that these days though.