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39415Re: [scrumdevelopment] Estimating user story

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  • Michael Vizdos
    Jun 29, 2009
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      I'll try to address your questions in-line below... Useful links,
      comics, and blog postings about this topic are located at the end of
      this response (for those that want more details).

      Thank you,

      - Mike Vizdos

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      On Mon, Jun 29, 2009 at 4:40 AM, Vikas Atri<vikasait25@...> wrote:
      > I  have concerns over estimation methodology used in scrum.
      > Had been spawning across couple of sites, but wasnt satisfied.
      > Just want to know from others experience here that :
      > Does story points reflect size (vis-a-vis against traditional life cycle
      > estimations like function points)
      > I read it in couple of sites(scrum alliance/mountaingoatsoftware etc) that
      > poker technique is used in estimating (efforts) for user stories in sprint.
      > The size estimates (story points) are in fibonacci series order.
      > 1,2,3,5,8,13
      > 1> What all factors are considered to arrive at story points?

      I think Roy has done a great job at answering that one (nice)! Let us
      know if you have other questions. One thing I'd add is that in
      reality story points mean nothing outside of the team and can / should
      differ from team to team. One of the goals for using Story Points is
      to come to a more predictable velocity for the team.

      > 2>What do we really mean by these mere numbers like 1, 2 ,3...etc

      You can use any number sequence you'd like. I'd recommend what you
      have started in your next question...

      > 3> What is the logic of selecting fibonacci series while estimating
      > (efforts) for user story.

      That series is useful to me because they are easy numbers for a team
      to wrap their heads around, and people can make easier estimates over
      a 3 point versus 8 point story (see Mike Cohn's Planning Poker for
      more information). Also, once the series gets to about 20 (not 21), I
      usually just use 20, 40, and a question mark. Remember these are
      *estimates* based on the teams experience and having some number like
      21 or 42 starts to imply an accuracy that is, in reality, false.

      > 4> At what step are the user stories broken down into tasks ? Is it like
      > User story -> story points -> Efforts

      I usually break down User Stories into Tasks with the team during
      Sprint Planning. This is where I make the jump from points to "hours
      of remaining effort" that will help the team track to the burndown
      chart and get more focused on what "Done" starts really looking like.

      > 5>If above be the case then how can the efforts be justified against story
      > point numbers like 1,2,3,5...
      > i.e what is the basis of arriving at efforts from story points
      > (1,2,3,5,8,13)

      This one is hard to swallow. There is no correlation between story
      points and effort of hours remaining for a Sprint. I am sure that
      statement will spark some interesting comments so I'll leave it at

      > Regards,
      > Vikas

      Hope this helps.

      I have some comic strips on the topic (and blog entries specific to
      this topic) at:



      - mike vizdos
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