CIS 375 SOFTWARE ENGINEERING

UNIVERSITY OF MICHIGAN-DEARBORN

DR. BRUCE MAXIM, INSTRUCTOR

Date: 9/15/97

Week 2

PEOPLE = PERSONNEL:

Too few - low productivity.
Too many - low productivity.
(Due to increased lines of communication).

TYPES OF PERSONALITIES:

Goal: Matching people to the right job, for their personality type.

PROJECT TEAM ORGANIZATION TYPES:

Hierarchical:
(Works best for large scale, routine work).

Ego-less (Democratic):
(Good for more "cutting-edge" type of work).

FRAMEWORK OF ACTIVITIES:

Customer communication.
Planning.
Risk analysis.
Engineering.
Construction and release.
Customer evaluation.

COST ESTIMATION:

TYPES OF COSTS:

Facilities.
People.
Project methods and tools.

TYPES OF COST MODELS:

Experiential (derived from past experience).
Static (similar to regression, doesn't change with time).
Dynamic (often includes the effects of time).

EXPERT JUDGMENT (EXPERIENCED GUESSING):

A = The most pessimistic estimate.

B = The most likely estimate.

C = The most optimistic estimate.

(A + 4B + C)

Ê = 6

(Weighted average; where Ê = estimate).

DELPHI TECHNIQUE:

A group of experts, make "secret" guesses.
These "secret" guesses are used to obtain a group average.
The group average is presented to the group.
The group, once again makes "secret" guesses.
Individual guesses are again averaged.
If new average is different from previous, then goto (4).
Else Ê = new average.

WOLVERTON MODEL:

(Uses a software type matrix):

{old, new} {easy, moderate, hard}.

Estimate models in terms of: lines of code.

C(k) = S(k) - C_i,_j(k)

Cost of module k = Size of module k - Value from matrix.

System = C(k).

FUNCTION POINTS:

(Not dependent on estimating lines of code).

Parameter Simple + Average + Complex = F_i

Distinct input items 3( ) + 4( ) + 6( ) = ?

Output screens/reports 4( ) + 5( ) + 7( ) = ?

Types of user queries 3( ) + 4( ) + 6( ) = ?

Number of files 7( ) + 10( ) + 15( ) = ?

External interface 5( ) + 7( ) + 10( ) = ?

Total = ?

# of F.P.'s = T_(total) ([0.65 + 0.01]_{(empirical
constants)} Q)

{Q = score from questionnaire}

FUNCTION POINT QUESTIONNAIRE:

(importance of {0-5; 0 = minimal & 5 = essential})

Backup.
Data communication.
Distributed processes.
Optimal performance.
Heavily used operating system.
On-line data security.
Multiple screens.
On-line master file update.
Complex inputs, queries, outputs.
Complex internal processing.
Reusable code.
Conversion or installation.
Multiple user sites.
Ease of use.

Cost of producing one function point? May be organization specific.

PROBLEMS WITH EXPERT JUDGMENT:

It is subjective. (consensus is difficult to achieve)
Extrapolating from one project to another may be difficult.
Users and project managers tend not to estimate costs very well.
Cost matrices require periodic updates.

Date: 9/17/97

Week 2

REGRESSION AND CORRELATION.

Mean = (x_i)/n

Variance = (x_i²)/n - (mean)²

Covariance _xy = (x_i y_i)/n - (x)(y)

Correlation = r

Regression; y = mx + b

X	Y	X^2	*XY**	Y^2
1	1	1	1	1
3	2	9	6	4
4	4	16	16	16
6	4	36	24	16
8	5	64	40	25
9	7	81	63	49
11	8	121	88	64
14	9	190	126	81
S= 56	40	524	364	256

REGRESSION MODELS

1. Linear Model

E = C_o + C_ix

{Effort in Person Months} {Intercept} {Regression Coefficient}

Static Non-Linear Model

E = C_o+ C_ix x_i²ⁱ

ⁱ⁼¹

Often rewritten using size of code as a factor

E = a + b S^c m (x)

{where a, b & c are constants, S = size, m = multiplier, and x = C_ix x_i²ⁱ }

COCOMO MODEL

COnstructive COst MOdel

Contains 3 levels

1. Basic: Computes software development effort (and cost) as a function of program size, expressed in estimated lines of code.

2. Intermediate: Computes software development effort as a function of program size and a set of "cost drivers" that include subjective assessments of product, hardware, personnel, and project attributes.

3. Detailed: Includes all characteristics of the intermediate version with an assessment of the cost driver's impact on each step (analysis, design, ect.) of the software engineering process.

Model: E = a S^b m(x)

BASIC INTERMEDIATE

MODE a b a b

Organic 2.4 1.05 3.2 1.05

Semidetached 3.0 1.12 3.0 1.12

Embedded 3.6 1.20 2.8 1.20

in the basic COCOMO model x=1

in the intermediate model a questionnaire is used

Product Attributes Computer Attributes

RELY Reliability TIME Execution Time

DATA Size of database STOR Amount of Storage

CPLX Complexity of System VIRT Virtual Volatility

* * TURN Response Time

Personnel Project

ACAP Analyst Capabilities MODP Modern Practices

AEXP Analyst Experience TOOL Software Tools

PCAP Programmer Capabilities SCED Development Schedule

PEXP Programmer Experience * *

VEXP Machine Experience * *

LEXP Language Experience * *

Parameter	Simple	+	Average	+	Complex	=	F_i
Distinct input items	3( )	+	4( )	+	6( )	=	?
Output screens/reports	4( )	+	5( )	+	7( )	=	?
Types of user queries	3( )	+	4( )	+	6( )	=	?
Number of files	7( )	+	10( )	+	15( )	=	?
External interface	5( )	+	7( )	+	10( )	=	?
					Total	=	?

	BASIC		INTERMEDIATE
MODE	a	b	a	b
Organic	2.4	1.05	3.2	1.05
Semidetached	3.0	1.12	3.0	1.12
Embedded	3.6	1.20	2.8	1.20

Product Attributes		Computer Attributes
RELY	Reliability	TIME	Execution Time
DATA	Size of database	STOR	Amount of Storage
CPLX	Complexity of System	VIRT	Virtual Volatility
*	*	TURN	Response Time

Personnel		Project
ACAP	Analyst Capabilities	MODP	Modern Practices
AEXP	Analyst Experience	TOOL	Software Tools
PCAP	Programmer Capabilities	SCED	Development Schedule
PEXP	Programmer Experience	*	*
VEXP	Machine Experience	*	*
LEXP	Language Experience	*	*