Saturday, 1 December 2012

Do "Task Hours" add anything in Scrum (Agile)?

What do task hours add to the overall process in scrum?

This was a question that has arisen from all team members in both instances that I've helped teams switch over to scrum. The benefits of artifacts like the comparative story point estimation, the 2 week sprints, stand-ups and the end of sprint demo have been self evident to the team, but as one I think every team member has expressed dismay when it comes to task planning and estimating each task in hours. Left unchecked there is a natural tendency for people to actually begin to dread the start of each sprint purely due to the task planning session.

In my current role we've been lucky to investigate this further as a team.

The team sat down to discuss the problems it was experiencing with estimating tasks in hours and the following common themes appeared:

  • It is hard: Maybe it shouldn't be, but time estimation is hard! Story points are comparative and abstracted making them easier to determine, but time estimate is generally expected to be pretty exact and accurate. There is no getting away from the fact that time estimation is just plain difficult (and not enjoyable) for most people!
  • It takes too long: The discussion around how long a task will take takes time, each story might have 5+ tasks; so it could end up taking an hour just to task (and time estimate) a single story! It might be easy to agree in seconds that we need a task to add new functionality to a service, but a discussion to estimate the duration of the task will take several minutes, if not longer.
  • Outcome of one task affects the duration of a subsequent task: If you have two tasks, one to create / update Gherkin and another to create/update the bindings. How long the second task takes is directly proportional to how many features / scenarios change or are created in the first task. This is nigh on impossible to estimate at the task planning stage.
  • It doesn't involve all the team: When the testers are discussing an estimate for the testing task, the developers are under-utilised and vice versa. We tried having two task estimate discussions going on at the same time and that didn't work very well either.
  • Working to hours, rather than done: We all seemed to realise that there was a natural tendency to sometimes work to the hours rather than the definition of done! If you knew you only had 30 minutes left on the task estimate it is very hard to add those couple of extra tests that would really trap those edge cases - it's much easier to finish the task on time and put off those tests to another task that might finish earlier than estimated. This is re-enforced by the positive comments that generally arise from the "actual" hours line on the sprint burn down graph following the estimate line.
  • It ignores individual ability: A team is made up of individuals of varying abilities and knowledge. I might estimate a task to take an hour because I worked on something similar last sprint, or am familiar with that functionality, whilst somebody else with different experience will estimate the same task as 3 hours. We are both right in our own estimations, but we shouldn't be allocating tasks at this stage, so which estimate should you use?
  • Compromise reduces value of the process: Leading on from the previous point, if the individual time estimates for a task range from 1 hour to 3 hours, you are looking at a compromise - this tends to work for story points but doesn't lend itself to task hour estimates as it results in a very wobbly line in the burn down graph.
  • Discussing the difference for longer than the difference itself: Continuing this theme; the difference between the largest/smallest estimates may be an hour. If you have 7 people around the table, the moment you spend longer than 8-9 minutes discussing the task (it can happen) you've spent longer (in man hours) discussing it than the difference you are discussing!

Sitting down with the product owner, it was story points / velocity which gave them the confidence that we could deliver what we had committed to.

Sitting down with the scrum master, they understood the concerns of the team and in light of comments made by the product owner, agreed to run a trial sprint where stories would be tasked, but no hours would be assigned. A commitment was made by the team that we wouldn't slip back into a waterfall approach and that the ability to flag potential issues during they daily stand ups shouldn't suffer.

We are now in sprint 3 of our trial, and I'm happy to say that the removal of task hour estimation hasn't had any measurable negative impact. Personally, having worked in an agile environment for two years, it did seem strange to be missing the sprint burn-down graph, but now we are further into the trial it has just proven to us that it was just giving us false confidence without providing any actual benefit! Our velocity and ability to commit to / deliver stories hasn't seen any negative impact, whilst we've trimmed 3-4 hours off the task planning meeting every 2 weeks (14-28 man hours!) and everyone starts the sprint feeling ready for it, rather than worn down by the longer meetings that were needed for estimating the task hours!

If you and your team have reached the point where you now dread the start of new sprints purely due to task planning session, why not give dropping the "hours" estimating part of task planning a go and let me know how it worked out for you.

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