Source : Free On-Line Dictionary of Computing

coefficient of X
     
        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, 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* emphasises 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".
     
        [{Jargon File}]
     
        (1994-11-29)