Choice of methods based on situation

3rd semesterAutumn 2015

Agenda There is a lot of different methods, a method should be chosen based on the

situation and perhaps be adapted continuously

Student presentations Nos: Agile Thedor: XP

Two topics for today Decision making (Simonsen and Buelens & Poucke) Parameters for choosing methods (Boehm)

Systems development methods and decision theory

Methods are based on a specific decision theory Directions – on how to make decisions Assumptions – the relevance of information in relation to making

decisions Rationality – basic ideas concerning reasoning

By choosing a methods you choose the inherent decision theory /approach

Decision-making theoryThree classical theories Individual:

Economic man Administrative man Muddling through

Group Decision hierarchies Garbage can Prisoner's’ dilemma

Prescriptive vs. descriptive

Economic man(perfect rationality) Known goals Known alternatives Ranking of goals Optimal choice

Transitive preference structure An ideal – no possible in reality

Process: Waterfall model / plan driven / predictive Infinite development process

Product: (Total) Information systems Information overload

Economic man- reflection XP?

Your self ?

Relevant situations?

Irrelevant situations?

Administrative man(limited rationality)

Man’s limited ability to handle information Simplification of problems Cost of handling information Limited uncovering of alternatives Satisfactory choices (not optimal)

Process: Modified waterfall model / iterative and incremental

Product: Information selection and aggregation

Administrative man(limited rationality) XP?

Your self ?

Relevant situations?

Irrelevant situations?

Muddling through(searching and learning processes) Goals and means are unknown Goals adapt to the means Small steps Learning process

Process: Agile (adaptive) process

Product: Close to traditions

Tradition and transcendence

Muddling through - reflection

XP?

Your self ?

Relevant situations?

Irrelevant situations?

Decision hierarchies Individuals have limited decision capacity Stepwise solutions - reduction of complexity Framework management F = frame / V = value

VF

VF

VF

Analysis

Design

RealizationEnvironment (External)(Frames/alternatives)

Organization (internal)(Values/preferences)

Garbage can Anarchy Organizations have unclear goals and changing participants Coincidentally ‘collision’ of

Occasions Problems Solutions Participants

Prisoner’s dilemma Game theory based on incomplete information Two individuals can either cooperate or betray each other Two "rational" individuals might not cooperate

even if it appears that it is in their best interests to do so

The dilemma: Two criminals imprisoned in solitary with no means of communicating with the other If A and B each betray the other, each of them serves 2 years in prison If A betrays B but B remains silent, A will be set free and B will serve 3

years in prison (and vice versa) If A and B both remain silent, both of them will only serve 1 year in prison

(on the lesser charge)

Pursuing individual reward logically leads both of the prisoners to betray In reality, humans display a systematic bias towards cooperative behavior

Balancing agility and discipline (Boehm)Criteria's for choosing the right method

Size Number of participant

Mission’s criticality Consequences/loss due to impact of errors

Skills Level of experience

Dynamic Number of changes pr. month in %

Culture Number that thrives on chaos – numbers that thrives on order

Skill levels Level -1: They should be rapidly identified and found other work to do!!

Level 1B: Less experienced developers They can function well in performing straightforward software

development in a stable situation They will slow down an agile team trying to cope with rapid change

Level 1A: They can function well on agile or disciplined teams if there are enough

Level 2 developers to guide them

Level 2: They can function well in managing a small, known agile or disciplined project But need the guidance of Level 3 people on a large or unknown projects

Level 3: Very experienced Can manage both agile and disciplined projects

Boehm’s model

Example

Exercise Argue for why being in the periphery favours a disciplined approach Argue for why being near the centre favours an agile approach

Wouldn’t a small highly skilled development team always be rather succesful?