
Estimate by
comparing work to do with work already done
Obtain an
estimate of the work remaining to do by breaking it into pieces that resemble
work already done, and assigning a similar expected effort.
This
pattern or a suitable alternative is a prerequisite for CompletionHeadroom. It may be that there are pieces of work that seem to have no
comparable predecessors. It is likely
that these will be higher risk, possibly architecturally significant. They should thus be candidates for prioritisation.
When a team is just starting working
together, there will be no preceding work to compare, and effort in the first tasks
will be affected by learning curves. Thus
estimates are likely to be poor or non-existent early in the project, but
settle down once learning curves flatten and feedback on prior estimates is
assimilated.