There are two, essentially unrelated, processes of converting things into numbers, and you should use different terminology for each, as they are different processes.
The first kind of conversion relies on, essentially independent, mapping of described experiences into numbers. This is usually known as coding and produces codes. A good example are library classification. The only properties of numbers which are exploited here is their endless availability (you're not going to run out of numbers), their lack of ambiguity as pure names,the availability of ranges, and their ability to be ordered. Beyond the library, this is a common technique in, for example, handling free text responses to questionnaires and is common in some branches of the social sciences.
The second kind of conversion considers the experience to be a quantity -- an analogue to some continuous quantity -- and is known as quantifying. Here, many more properties of numbers are potentially used and issues such as precision, accuracy, linearity, bias, distribution, and so on, arise when developing the quantifying method. With a quantity, many more of the properties of numbers may be applied, such as multiplication, addition, and so on to produce at least superficially meaningful answers (which can be beguiling).
For example three lots of four Quality-Adjusted Life Years is twelve Quality Adjusted Life-Years which an advocate of this technique would consider more than superficially meaningful. However no one at all would claim in Dewey library classification that two time the New Testament (225) was Romanian (550).
In discussing QUALY, and more generally in the dismal science, you are dealing with quantifying. However, unless you are an un-questioning advocate of utilitarianism (sadly, almost a creed among economists), you will presumably need to be aware of and describe alternative techniques of converting to numbers for processing that are better described as coding.