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From chaos to goals: Requirements change can be predicted. Johan F. Hoorn Vrije Universiteit Computer Science Information Management and Software Engineering [email protected] Contents. Status Problem Analysis Model Method Case Results Conclusions. Johan F. Hoorn, 2004.

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From chaos to goals:

Requirements change

can be predicted

Johan F. Hoorn

Vrije Universiteit

Computer Science

Information Management

and Software Engineering

[email protected]


Contents

  • Status

  • Problem

  • Analysis

  • Model

  • Method

  • Case

  • Results

  • Conclusions

Johan F. Hoorn, 2004


Status

  • Sept. 1, 2001 – Aug. 31, 2005

  • Supervisors: Gerrit van der Veer

    Hans van Vliet

  • Four international publications

  • Industries:

  • Human-Machine Interaction

Johan F. Hoorn, 2004


Business model 1

Traditional office

Mainframe with

thin clients

Business model 2

Flexible workplace

Laptops with

bluetooth

A change request during development is

extremely costly and frustrating

Problem

  • Requirements change

Johan F. Hoorn, 2004


From chaos to goals:

Nobody knows how

requirements change

can be predicted


Analysis

  • Where do change requests come from?

Business model 1

Business model 2

  • Change in business sub goals

    - Main goals:Profit

    - Sub goals:Cost-effectiveness, efficiency

  • How come business goals change?

  • Change in sub goals (strategic management)

    - Main goals:Earn my living

    - Sub goals:Fire employees (not me),

    improve IT to guarantee same output

Johan F. Hoorn, 2004


Model

  • Change of Stakeholder Requirements

    (CoStaR)(Hoorn & Van der Veer, 2003a; 2003b)

One of the hypotheses:

Valence

Requirements

Goals

Stakeholder evaluation:

Does a system feature support my goals?

Does a system feature obstruct my goals?

(after Frijda, 1986)

Johan F. Hoorn, 2004


Method

  • REquest, the Requirements Engineering

    questionnaire

General approach: Items that combine

- a must or a won’t requirement, with

- support or obstruction of

- a goal to achieve with the system or

a goal state to avoid,

scored for agreement on a 6-point Likert scale

Johan F. Hoorn, 2004


Case

  • Eighteen managers of a logistic

    warehouse management system

must/won’tsupport/obstructgoal approach/avoid

E-mail orderingincreasesefficiency

E-mail orderingdecreasesefficiency

E-mail orderingincreasesinefficiency

E-mail orderingdecreasesinefficiency

Paper ordering formsincreaseefficiency

Paper ordering forms decreaseefficiency

Paper ordering forms increaseinefficiency

Paper ordering forms decreaseinefficiency

Example items

Johan F. Hoorn, 2004


Results (1)

  • Original hypothesis:

Valence

Requirements

Goals

- Indeed, goals, valence, and requirements

all evoked significant effects on agreement

to requirements statements

Johan F. Hoorn, 2004


Results (2)

↑ Grand mean agreement

5

4

3.67

(1.14)

2.78

3

2.5

2.41

(1.04)

2.19

(.96)

1.8

(.98)

2

(1.44)

(1.09)

1

0

Goals (to

Goals (to

Requirements

Requirements

Valence

Valence

approach)

avoid)

(must have)

(won't have)

(support)

(obstruct)

MANOVA (must vs won’t) * (support vs obstruct) * (goal approach vs avoid)

Pillai’s Trace = .51, F(2,16)= 8.40, p= .003, ηp2= .51

Johan F. Hoorn, 2004


- Goal-driven RE models should be unipolar

Goals

(approach)

Requirements

(must have)

Valence

(support)

Valence

(obstruct)

Goals

(avoid)

Requirements

(won’t have)

Results (3)

  • Original hypothesis:

Valence

Requirements

Goals

  • Bipolar conception does not hold

  • Regression: R2= .03, R2adj= -.03, F(1,16)= .47, p= .504

Johan F. Hoorn, 2004


Results (4)

  • However, original structure should be

    completely revised

Goals

Requirements

(to approach)

(won’t have)

Valence

(support)

Valence

(obstruct)

Requirements

Goals

(must have)

(to avoid)

Johan F. Hoorn, 2004


no predictive power

Yet, valence does have influence.

Requirements vs. goals: Parameter coefficient= -.56, t= -4.04, p= .001, ηp2= .49

no predictive power

70%!!

90%!!

Results (5)

R2= .79, R2adj= .70

F(5,12)= 9.01, p= .001

Goals

(approach)

Requirements

(won’t have)

Valence

(support)

Valence is a moderator!

Valence

(support)

Goals

(avoid)

Requirements

(must have)

R2= .93, R2adj= .90

F(5,12)= 30.30, p= .000

Johan F. Hoorn, 2004


Conclusions (1)

  • RE should be oriented to goals

  • Requirements validation should be done

  • with structured questionnaires

  • (e.g., REquest)

  • Goals to achieve predict won’t requirements

  • Goal states to avoid predict must requirems

  • Like the weather, valence does not predict

  • mood (i.e. agreement) but it does influence it

Johan F. Hoorn, 2004


Conclusions (2)

  • Most important RE questions are:

  • What are the things you want to achieve

    with the system?

  • What should the system NOT have to

    support that?

  • What are the things you want to avoid

  • with the system?

  • What should the system offer to support

    that?

Johan F. Hoorn, 2004


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