About staffing level estimation

1. Software Engineering
Staffing Level Estimation
Submitted by,
M. Kavitha,
II – M.Sc (CS&IT),
Nadar Saraswathi College
of Arts & Science, Theni.

2. Staffing level estimation :
* The number of personnel required throughout a
software development project is not constant.
* Planning and analysis are performed by a small group
of people, architectural design by a large, but still group and
details design a large number of people.
* Implementation and system testing require the largest
number of people.
* Maintenance may require numerous personnel but the
number should decrease in a short time.

3. * In 1958, Norden research and development project.
Cycles :
A. Planning
B. Design
C. Prototype
D. Product
E. Modification

4. * A cycle of planning, design, prototype, development
and use with the corresponding personnel.
* Any particular point on the Rayleigh curve represents
the number of full-time equivalent personnel at that instants in
time (NOR58).
* The Rayleigh curve is specified by two parameters, td
the time at which the curve its maximum value.
* Then K the total area under the curve which represents
the total effort required for the project.

5. E = K / t2
d t e –t2/2t2
d
Fig 2 : The Rayleigh curve of effort vs. time

6. In 1976, Putnum reported that the personnel level of
effort required throughout the life cycle.
Fig 3 : Putnum’s interpretation of Rayleigh curve(PUT76)

7. A. Design and coding (15%)
B. Test and validation (20%)
C. Extension (10%)
D. Modification (25%)
E. Maintenance (20%)
F. Management (10%)
* The planning requirements analysis and functional
design in the project curve.
* Boehm the Rayleigh is reasonably accurate
estimator of personnel development cycle.
* The development cycle from architectural design
through implementation and system testing if the portion of
the curve between 0.3td and 1.7td.

8. Where ,
PM - estimated number of programmer months
for product development (excluding planning and analysis)
TDEV - estimated development time.
FSP – Full – time Software personnel.

9. * FSP required at any particular time t, where t is
in the range 0.3td to 1.7td.
* Then td is still the time of peak staff requirements
but it is no longer interpreted as the elapsed development
time.
* The plot of the personnel requirement as a
function of time for a 32-KDSI, 91-PM.
COCOMO Rayleigh
Design System
test
FSP
t, months

10. Activity
Effort Schedule
32 KDSI 128 KDSI 32 KDSI 128 KDSI
Plans and
requirements 6% 6% 12% 13%
Architectural
design 16% 16% 19% 19%
Detailed design 24% 24% Combined value :
Coding and unit
test 38% 36% 55% 51%
System test 22% 25% 26% 30%
Table 1 : Distribution of effort for application programs

11. Activity
Effort Schedule Personnel
32
KDSI
128
KDSI
32
KDSI
128
KDSI
32
KDSI
128
KDSI
Plans and
requirements 5PM 24PM 1.2MO 3.1MO 2.9FSP 8 FSP
Architectural
design 15PM 63MM 2.2MO 4.6MO 5.6FSP 14FSP
Detailed design 22PM 90MM Combined Values :
Implementation
34PM 141MM 7.7MO 12.2MO 7.3FSP 19FSP
System test 20OM 90MM 7.2MO 7.2MO 5.6FSP 14FSP
Table 2 : Distribution of effort, schedule and personnel

12. * Boehm also presents tables that specify the of
effort and schedule in a software development project.
* The total number of programmer months and total
development time can be used estimate the actual number
of programmer months and elapsed time for each activity.
* An estimate of the number of full time software
personnel required in each phase of software development
and divided number of programmer month.

13. Thank You