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We have only just recently starting using Kanban, so we have little or no predictability data about how long epics and stories take to move through our system.

How do we give the business an idea of how long epics and stories will take to exit the system?

  • What system did you use before? If a few team members have experience with similar projects, they can probably supply some rough estimates to get you started. (Very rough estimates. You should significantly increase these estimates due to the difficulties of settling into a new system.) – Llewellyn Jul 2 at 18:02
  • Ok thanks I was thinking of doing T-shirt sizing with some retrospective baselines – user32613 Jul 8 at 21:00
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Ideally you wait until a number of stories and epics have passed through your Kanban board and then use that data to help estimate future cycle times.

If you absolutely need to provide estimates from day one then you can use the following approach:

  • Break the stories down in to sub-tasks
  • Estimate the hours for each sub-task
  • Calculate the capacity of the team (number in the team multiplied by the available hours per person)
  • Use this data to give some initial estimates of cycle time

This is similar to traditional development estimating and as such is vulnerable to over-optimism, pressure to size estimates based on business needs, etc. There is also an argument that this kind of estimating is a form of waste as it takes the team time to do but provides only limited value.

I would recommend that if you go with this approach that you drop it as soon as you have a reasonable amount of cycle time data available (say after a few weeks or a month).

  • Thanks for reply. I don’t think this is possible as it would be super expensive to take a bunch of high level epics and break them down when we are some way off completing them. Just out of interest. Would T-shirt sizing at epic level be worthless in your opinion? – user32613 Jul 3 at 6:29
  • T-shirt sizing of epics makes more sense when you have historical data for the team. The challenge with epics is that they often lead to discovery - i.e. they may just be the tip of the iceberg. – Barnaby Golden Jul 3 at 8:40
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Actually you can use little's law to do this, assuming you have at least some (at least 2 I guess) items leaving the system (i.e. they were started a long time ago before you started using Kanban) and you have a throughput. (It is not required to have any items traveling all though the system - I did this at a company that had lead times of 300 days plus, so weren't going to wait that long before predicting lead times)

Expected Average Lead Time = Current WIP / Throughput

  • This is true. I do have epics and stories which we completed using sprints. I guess it’s not as accurate but it’s something. – user32613 Jul 3 at 7:33
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That sort of system is all about trends. You can't provide data you don't have, so you need to start building it up by doing the work.

  • Would you mind elaborating what you mean by trends. Are you talking about control charts and cumulative charts? – user32613 Jul 2 at 17:40
  • Should we not T-shirt size the epics? – user32613 Jul 2 at 17:41
  • It is based in empirical process control, so the only way to predict future results is based on past experience. If you have no past data to draw on, your prediction confidence would be zero. – Daniel Jul 3 at 2:46
  • That isn't to say that people can't make educated guesses, but much of the dysfunction we see around estimates are when people treat educated guesses as if they are empirical estimates – Daniel Jul 3 at 3:33

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