Adapted from Manager’s Handbook for Software Development, Revision 1. Document number SEL-84-101.
Greenbelt, Maryland: Goddard Space Flight Center, NASA, 1990.
Project
Phase |
Input Data
for Estimate |
Size
Estimate |
Effort
Estimate |
Schedule
Estimate |
Uncertainty
Range 1 |
|
End of
Requirements
Analysis |
Number of
Subsystems |
11,000 lines
of code2
per subsystem |
3000 hours
per
subsystem |
Multiply number of
subsystems by 83
weeks and divide
by number of staff
members |
+75%
-43% |
End of
Preliminary
Design |
Number of
functions and/or
routines (units) |
190 lines of
code per unit |
52 hours
per unit |
Multiply number of
units by 1.45 weeks
and divide by number
of staff members |
+40%
-29% |
End of
Detailed
Design |
Number of
slightly modified
(N) or reused
verbatim (R) units |
Lines of
code = 200 *
(N + 0.2R) |
0.31 hours
per line of
code |
Multiply lines of code
by 0.0087 weeks
and divide by number
of staff members |
+25%
-20% |
End of
Implementation |
Current size in
lines of code
Effort
expended
to date
Schedule
expended
to date |
Add 26% to
current size
(for growth
during testing) |
Add 43% to
effort already
expended (to
compute
effort to
complete) |
Add 54% to
schedule already
expended |
+10%
-9% |
End of
System
Testing |
Effort
expended
to date |
Final product
size has
been reached |
Add 11% to
effort already
expended
(to compute
effort to
complete) |
Add 18% to
schedule already
expended |
+5%
-5% |
1To allow for staff turnover, growth in requirements, and so on, conservative management practice calls for using estimates
that lie between the predicted value and the upper bound.
2 "Line of code" includes all source statements, including comments and blank lines