Almost everyone concerned with developing software, or with managing the
development of some software, will at some time need to be able to estimate or
measure its size. The key uses of software sizes are:
Project Estimating
“How big is it?” is the first question that naturally springs to mind
when a Project Manager is faced with a demand to estimate the cost of
developing a new piece of software. If we can put a size measure on the
requirements for a new piece of software then we have taken the first vital
step towards estimating the cost and time that will be needed for its
development.
Project Performance Measurement
In practically any industry, the ability to measure performance is
critical for understanding and improving performance. ‘Productivity’ for
example, is usually defined as ‘the amount of product delivered divided by the
effort needed’. For software development this is interpreted as ‘software
size’/’project effort’.
‘Software size’ is taken as our measure of project work-output.
Other important software project development performance measures
include:
·
‘Speed of delivery’ = ‘Software size / elapsed time
·
‘Defect density’ = Number of defects identified in a given period / ‘software
size’.
If you wish to compare your organisation’s project performance measures
against another organisation’s, or against external benchmark performance
measures, then clearly standardised software size measures are essential.
Project Scope Control
If a supplier gives an estimate to a customer for the cost of a new
development, and the customer then adds in new requirements, the supplier will
wish to respond by either increasing the cost estimate or by negotiating about
the scope of the customer’s requirements. Either way, the ability to
measure a size of the software and of the proposed changes is a critical
parameter for both parties in the negotiations.
Software Asset Valuation
Most large organisations, whether in the private or public sectors have
now accumulated vast amounts of software over the latter half of the twentieth
century. Putting a size on this asset or parts of it can be valuable when
it comes to estimating the replacement cost. Some organisations,
especially in financial services, use a size measure to help value their asset
so that it can appear on the organisation’s balance sheet.
Software contract control
If your job is to control a software supply contract, then it can be
critically important to be able to size the software for all the purposes
described above.