coefficient of X

coefficient of X n.  Hackish speech makes heavy use of
   pseudo-mathematical metaphors.  Four particularly important
   ones involve the terms `coefficient', `factor', `index', and
   `quotient'.  They are often loosely applied to things you cannot
   really be quantitative about, but there are subtle distinctions
   among them that convey information about the way the speaker
   mentally models whatever he or she is describing.

   `Foo factor' and `foo quotient' tend to describe something for
   which the issue is one of presence or absence.  The canonical
   example is {fudge factor}.  It's not important how much you're
   fudging; the term simply acknowledges that some fudging is needed.
   You might talk of liking a movie for its silliness factor.
   Quotient tends to imply that the property is a ratio of two
   opposing factors: "I would have won except for my luck quotient."
   This could also be "I would have won except for the luck factor",
   but using *quotient* emphasizes that it was bad luck
   overpowering good luck (or someone else's good luck overpowering
   your own).

   `Foo index' and `coefficient of foo' both tend to imply
   that foo is, if not strictly measurable, at least something that
   can be larger or smaller.  Thus, you might refer to a paper or
   person as having a `high bogosity index', whereas you would be less
   likely to speak of a `high bogosity factor'.  `Foo index' suggests
   that foo is a condensation of many quantities, as in the mundane
   cost-of-living index; `coefficient of foo' suggests that foo is a
   fundamental quantity, as in a coefficient of friction.  The choice
   between these terms is often one of personal preference; e.g., some
   people might feel that bogosity is a fundamental attribute and thus
   say `coefficient of bogosity', whereas others might feel it is a
   combination of factors and thus say `bogosity index'.