Size data in SLIM tools consists of two
components:
•Function unit count. This is the number of top-level
function units (a sizing component like SLOC, Function Points, Requirements,
Agile Stories, etc.) delivered by the project in the current release.
Function units fall into two categories:
•The Base Size Unit is the “least common denominator” of size
components. Roughly equivalent to writing a line of code, it always has a
gearing factor of 1. Because it is used to normalize size data for projects
sized in different components like Stories, Use Cases, or Function points,
neither the name nor the gearing factor for the Base Size unit can be
edited. The acronym can be customized.
•Other Function Units. This category includes all sizing components
other than the base size unit with a gearing factor greater than 1. Examples
include Function Points, Stories, Requirements, Objects, Use Cases.
•Gearing Factor. The gearing factor represents the average number of base size units needed to implement your chosen Function Unit. So, for example, if it takes an average of 50 Base Size units to implement an average function point, the gearing factor for Function Points will be 50. To compare projects with different sizing units in a meaningful way, it is necessary to identify the smallest common size unit. Without this common reference point, it would be impossible to compare projects sized in Objects with projects sized in Function Points, as there would be no way to determine their size relative to each other. QSM uses the concept of the gearing factor (the ratio of Base Size Units / any larger size unit) to relate various sizing units such as Modules, Screens, or even Web pages back to a common scale: the Base Size Unit.
SLOC (and the more generic “IUs”) have been used successfully as a Base Size Unit for many years. They provide a common reference point across different languages, sizing methods, and development paradigms They also make it possible for QSM to apply the same family of PI’s and industry trend lines to a variety of projects measured in different sizing units. With the advent of GUI languages, there may be situations where SLOC is no longer a meaningful unit. For this reason, you may designate an alternate base size unit acronym, keeping in mind that the unit label you choose should carry approximately the same amount of time and effort as writing a line of code. The idea is to preserve a common frame of reference, while allowing the user the flexibility to choose a base size unit that accurately reflects the actual work content being performed.
The default gearing factor you supply here will be used to initialize new size records created in SLIM-Collaborate, but it may be replaced with a more appropriate gearing factor on a project-by-project basis.