Something can be estimated therefore it is "estimatable"?

While the meaning of the word estimatable is quite clear, it is not a real English word. Is there such a real English word with the same meaning?

In case it helps, this is based on the INVEST user stories in Agile¹. The E stands for Estimatable aka "should be be possible to estimate".

I am, of course, happy for such a word not to exist. If so, how would you phrase it so that it still makes sense in the above context?

_{^{1: Erick G Hagstrom pointed that the INVEST was coined by Bill Wake who uses E – Estimable.}}

Solution 1:

Why is estimatable not a real English word? The -able suffix is productive, and dictionaries very often do not include words which can be deduced from their constituent parts, particularly since they can only include words in reasonably common usage. There is a trade-off: if they do not include words which can be broken down easily and their component parts looked up, there is more space for slightly less common words which can't be deduced as easily.

ODO has

-able suffix

forming adjectives meaning:
1. able to be:
    calculable

Estimatable means able to be estimated.

Solution 2:

Estimable certainly is a real English word, and, as any good dictionary will tell you, it means 'worthy of great respect'. It doesn't mean is 'capable of being estimated'. I know of no single word that means that.

Solution 3:

As Andrew Leach says in his answer, it is not not a real word; in fact, Google Scholar shows 1880 results of the word "estimatable".

While not a large enough number of uses to make it standard usage, a quick scroll shows that most of the publications are in mathematics and statistics (and, of course, here the results are limited to scholarly articles). The sciences often "create" words, and these words can well become standard usage within a particular field. A similar example would be "rounding", as in "going on rounds", commonly used in nursing but not in standard dictionaries with that definition.

My search for "estimatable" in normal Google mostly brings up either the same sort of usage or questions about its usage (such as this).

As such, I would say it is safe to use in the particular context in which it does currently get used, but not formally elsewhere.

Unfortunately, I don't have any good alternatives off the top of my head.