This column is the fifth in a series about estimating.
The first was in the July 1996 issue. This month, we talk
about how to produce the conceptual design, define the
objects in that conceptual design, and estimate the LOC
they contain. The prior columns in this series gave an
overview of estimating, defined software size, introduced
the subject of proxies, and showed how to categorize size
data so you can use them in size estimating. If you have
not read these earlier columns, you should look at them
first to understand the context for this discussion and
to see how these various estimating topics relate. To
repeat what I said in the previous columns, the
estimating method described here is called PROBE. If you
want to quickly learn more about PROBE, you should read
my book A Discipline for
Software Engineering, from
Addison Wesley. This book introduces the Personal
Software Process (PSP)SM, which is an orderly
and defined way for software engineers to do their work.
This column continues the discussion of how to make size estimates.
To make a project plan, you need a resource estimate and, to estimate
resources, you need to estimate the size of the product you plan to
build. Also, to make a good size estimate, you need historical data on
the sizes of the programs you have previously written. This column
describes how to use these data to make the size estimate.