Re: [unrev-II] Intrinsic and Extrinsic Ratings wrt IBIS

From: Peter Jones (
Date: Wed Oct 31 2001 - 14:18:58 PST

  • Next message: Peter Jones: "Re: [unrev-II] Intrinsic and Extrinsic Ratings wrt IBIS"

    Adding scoped weightings sounds v. interesting.

    Eric Armstrong wrote:
    > Thinking about it, those observations capture the notion of
    > :"intrinsic" vs. "extrinsic" (project-relative) rankings.

    But adding more thought to the pile, it seems to me that, as you say, the
    evaluation criteria are crucial. So perhaps there aren't just intrinsic and
    extrinsic rankings really, but a morass of weighting dimensions depending on
    the range of sets of criteria involved.

    Perhaps that's why IBIS doesn't do that. It's a deliberate limitation to
    speed consensus development. (?)


    ----- Original Message -----
    From: "Eric Armstrong" <>
    To: <>
    Sent: Wednesday, October 31, 2001 9:22 PM
    Subject: [unrev-II] Intrinsic and Extrinsic Ratings wrt IBIS

    > Good questions.
    > In the textual representation I keep for design documents,
    > there is a more less equal "weight" of the symbols:
    > +: This is a thought that favors the idea
    > -: This is a thought that discourages it.
    > However:
    > a) It is good to be able to record thoughts without
    > determining in advance if they are for or against,
    > and have the ability to decide that later.
    > b) You are absolutely right that the content of a single
    > item can outweigh a whole flock of others. There
    > is no good way to cature that idea that I have seen
    > so far.
    > In part, I think that is a "background" thing, that depends
    > in large part on your evaluation heuristics -- what you
    > consider important. So this structure:
    > i: An idea
    > +: Produces an efficient implementation
    > -: Doesn't have a very good interface.
    > Produces a huge negative that totally outweighs the positive
    > if you are an interface specialist or if you are designing a
    > product in which the interface is crucial. On other hand,
    > the positive totally blows away the negative if you are a
    > performance specialist or building a batch-mode system
    > that will be configured once and run a million times
    > thereafter.
    > Thinking about it, those observations capture the notion of
    > :"intrinsic" vs. "extrinsic" (project-relative) rankings. A bubble
    > sort has a + in that it is fast to code, and a negative in that it is
    > inefficient for large amounts of unsorted data. Those are "intrinsic"
    > evalations -- truisms that stand unchanged, regardless of
    > circumstances.
    > When making the decision as to which sort to implement
    > for a particlar project, however, those rankings need to
    > "feed into" the evaluation criteria, using either a verbal or
    > automated equivalent of:
    > 1) This is a quick and dirty, one-time program, so
    > a bubble sort is great. (Big weighting on the plus.)
    > or
    > 2) This is something that will run for years on very
    > large sets of data, so a bubble sort is really not a
    > good idea (Big weighting on the negative).
    > The intrinsic ratings represent "knowledge" -- things to
    > know about bubble sort, in addition to the mechanics of
    > constructing one.
    > The extrinsic weightings, represent the product of intrinsic
    > ratings relative to the project's design criteria -- the principles
    > used to make selections among competing design alternatives.
    > I suspect that many an IBIS-style conversation could be
    > improved by clearly distinguishing the two kinds of
    > information.
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