The Sizing tab gathers all information used to estimate and
measure project size in one place. In SLIM-Collaborate, it’s important to
understand what is meant by “size”. What you are trying to estimate is not
schedule, effort, or cost but the actual functionality implemented and delivered
by the project.
The most intuitive way to think about project size is
lines of code or elementary programming steps (base size units) required to
transform user requirements (“I want to create an airline reservation, print a
boarding pass, and record this information in a database accessible over the
Internet”) into the user interface and back end software that performs these
tasks. You can use any sizing component (base size units, function points,
requirements, etc.) that is practical for the work you will be performing and
the information you have on hand at the time estimates are required. If
the estimate is needed early on before the requirements are fully known, you
will likely use an abstract sizing method like sizing by analogy (comparing the
anticipated scope to a similar completed project or projects whose size is
known). Though such estimates are “rough order of magnitude” ones, they are
useful and can be refined later on when more data is available. If you have
requirements documents or perhaps your Agile team has identified and sized user
stories, you may use a sizing component like Requirements, Stories, or Story
Points. The trick is to match the size method to what you know or can
reasonably infer at the time the estimate is needed.
SLIM-Collaborate
provides some guidance in selecting a size method. For the Feasibility solution
method, SLIM-Collaborate automatically selects the Size Bin method and uses a
Medium size bin. If you know very little about the proposed system, assuming it
is “average sized” or selecting a smaller or larger bin based on intuition or
experience is enough to get you into the right “ballpark” on size. Later,
you can revisit the size estimate and change to a more detailed size method by
selecting another option from the dropdown.