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Re: Burn Up Charts

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  • Russ Rufer
    Since both the Silicon Valley Patterns Group list and Scrum Development list have been high traffic, I ve consolidated responses to Mike Cohn, David J.
    Message 1 of 64 , Apr 2, 2003
      Since both the Silicon Valley Patterns Group list and Scrum Development
      list have been high traffic, I've consolidated responses to Mike Cohn,
      David J. Anderson, Ron Jeffries, and John P. Gilman in this message.


      Mike Cohn wrote:
      > I assume the y-axis below is really “time spent” rather than features.

      Customers aren't asking to use up staff days--they're asking to
      implement features. Mythical man month arguments aside, one benefit of
      the burn up chart is that it allows you to track and understand your
      velocity. We described the burn-up chart in terms of features (e.g.
      rough estimates of cumulative story points) because relative difficulty
      of features is more easily (and accurately) estimated than staff days.
      (more on this below)

      A primary goal of the burn up chart is to illustrate the need (or
      opportunity) for scope negotiation, and to make these historical
      negotiations clear and distinct from changes in velocity.

      Measuring against planned features makes feature adjustment the easiest
      and most natural response to a projected problem.


      David J. Anderson wrote:
      > Hence, your chart would be a departure for Scrum. It
      > shows client-valued output, rather than level of
      > effort required to complete a deliverable.

      Yes. I think you've drawn a nice distinction. As I read them, the burn
      down chart shows how much money (~staff time) the project expected to
      spend at a series of historical points. The burn up chart shows
      historical progress toward a planned feature set. Both give some idea
      of whether the team is on track for delivery, with different emphasis on
      what should be done about mismatches (staffing change emphasis vs.
      feature scope emphasis).

      Given a known stable velocity it's arithmetic to transform between
      feature points and staff days. That's if you know your velocity to this
      accuracy early in a project? If you do, really, you could use either
      label for the y axis interchangeably. But if you don't (which is
      probably the case) I don't know how you would modify the chart using
      staff days to reflect your growing understanding.


      Mike Cohn wrote:
      > One concern I would have expected developers to have with this chart
      > would be the boss looking at it and seeing a high value on the y-axis:
      > “You mean we’ve spent 20,000 person-hours on that project!!!!”.

      Wouldn't the boss look at a burn down chart and say, "You mean we're
      going to spend 20,000 person hours on this project!!!"?


      David J. Anderson wrote:
      > Does your chart compare to the Cumulative Flow Diagram
      > I described here?
      >http://www.featuredrivendevelopment.com/node.php?id=515%22%3ECumulative

      Thanks for posting this link. Yes, the simple burn up chart looks like
      your Cumulative Flow Diagram. Chris Lopez notes (on the Silicon Valley
      Patterns Group list) that it isn't clear whether the Cumulative Flow
      Diagram uses a raw feature count or features scaled by difficulty. I
      had in mind that our feature axis would indicate scaled "feature
      points". I'm not sure what Phil Goodwin had in mind here since we
      haven't explicitly discussed this aspect.

      Please also have a look at the more complex version of the burn up chart
      that Phil posted to the Silicon Valley Patterns Group list. See the
      attachment "BurnUp3.jpg" in:

      http://groups.yahoo.com/group/siliconvalleypatterns/message/1597

      (Note: Phil also addresses Ron's acceptance test chart in this message.)


      John P. Gilman wrote:
      > Mary, I'm having a little trouble understanding what I'm seeing with
      > the horizontal "Expected Feature Set" lines. My best guess is that
      > I'm looking at feature creep over time with a reduction in the
      > expected features at the end of the sprint, but I'm sure this isn't
      > correct.

      Clearly the sample burn-up chart we depicted isn't an ideal, smooth
      running project. In fact I agree with John, a chart that looked like
      this one would probably indicate feature creep that had to be reined in.

      (Its nice that this feature creep could be distinguished from a change
      in velocity--can a burn down chart reveal such distinctions?)

      We were trying to show a clear case where scope negotiation was required
      to meet a target. Unfortunately we show a project that was almost never
      on track to deliver their planned features on the target date, but kept
      adding features.

      It would have been clearer had we not confused the sample chart by
      showing such a troubled project.

      A simpler case would be a project that didn't add features, but whose
      progress pointed out that the target wouldn't be hit--leading to a
      planned feature reduction (as a mid-course correction, not last minute).

      A more interesting case would show stronger than expected progress,
      justifying additional features because the team projects they can
      accommodate a more ambitious plan. Then indicate a sharp decline in
      velocity with a note on the date that 4 developers left the
      team--prompting a reduction in scope to keep the project on track.

      - Russ
    • Dave Hoover
      Mike, ... Agreed! ... I think we struggle with researching previous art because most of the leading agile thinkers are in the trenches, not in academia.
      Message 64 of 64 , Apr 12, 2003
        Mike,

        > I think it is fine to assume that it is "independent
        > thinking". This is a good thing because it confirms
        > that at least 2 people can reach the same conclusions
        > and can validate their experiences and explain
        > the world the same way.

        Agreed!

        > (You could always
        > ask the question the other way: Is the stuff
        > from "Growing Software" coming from somewhere else
        > since our stuff was published 5-7 years ago
        > i.e. PLOP3 proceedings, PLOPD4 book, etc. I think
        > it is safe to assume "independent thinking" because
        > our industry is famous for not researching
        > "previous art". In hard Science this would actually
        > be an embarrassment.)

        I think we struggle with researching "previous art" because most of the
        leading agile thinkers are in the trenches, not in academia. This is why I was
        excited when I saw the overlap between the Scrum book and "Growing
        Software". I figured that both the Scrum folks and Roy had probably not had
        the opportunity to find each other.

        I look forward to the outcome of future collaborations between agile thinkers
        who find complexity science applicable to software development.

        --Dave
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