Our development team is pretty new to the scrum process, so I would like to help refine our methods to make better use of it. In particular, I noticed that the correlation between story points and task hours is not very good. That is, we often have stories of lesser points decomposed into a total task hours greater than stories of higher points.
Now, I am aware that these are two separate estimation processes and that we should use the hours to estimate only the remaining work for a sprint while using the story points to compute a velocity and be able to predict the length of the release cycle or the amount of features we will be able to address. However, it seems to me that if sprint points and task hours don't correlate well, then we must be doing a bad job at estimating either one or both of these.
Since we only adjust the remaining work hours as opposed to recording the time spent, I can't easily tell if the problem is the initial task hour break-down or the story point estimates.
So, my question is whether we should deal with this and how? I can think of several ways to start dealing with this:
- Record time spent in a task and use this information as feedback to help refine our estimation process by retrospectively identifying user stories which we under/over estimated. But I am not convinced that we want to record this information and I anticipate resistance to it.
- At the planning phase, identify outliers after the task hour break-down process and look at these further. This way we could try to identify whether we misjudged the complexity of the story or if the task breakdown is missing some efforts or over-estimating the length of simple tasks. However, I'm afraid this would couple the two estimation efforts, which doesn't seem as the right thing to do either... This also assumes we would have decomposed all stories in the planning phase, otherwise we won't be able do much about stories which were misjudged.
- Another method to approach this would be to try to independently incorporate methods to enhance the estimation process and raise the team consciousness about the importance of estimation. Then just keep monitoring the correlation between story points and initial task hour break-down as an indicator of how we are doing and whether we need to keep working at it. I'm inclined to think that this is the best approach, but less pro-active.
What is the best way to approach this issue and/or what other suggestions are there for enhancing the estimation process in this context?