IE 423 Designing Decision Support Systems

Decision Making

Suppose-

You are hired (first job after graduation!!) by an elf working for a generic cookie company…to develop a decision support system to assist the elf in selecting ingredient suppliers for the cookie factory (which is in a rural cave since all of the hollow trees have been cut down by condominium developers).

Cookie DSS

Goal to select ingredient suppliers to

support the production of 10,000 cookies per day

Objectives to receive 1000 lbs. of flour per day quality flour delivered to the cave at the best price

Cookie DSSDefine Suppliers… Supplier name location price per lb. production capacity delivery capacity

truck capacity 4WD

Quality milled contaminants (bpp)

Reliability

Cookie DSSName Flour-r-us Flour City Elfen

Flour

Location near very far far

Price/lb. $1.00 $.70 $1.20

prodcap 1100 900 1200

truckcap 1000 1000 1000

4WD No Yes Yes

milled 9 9 9

bpp 1 0 4

reliability .95 .95 .70

Decision Making

Decision making – the act of selecting an action from a set of alternative actions. Select One:

Option A – Flour-r-us Option B – Flour City Option C – Elfen Flour

… that may be rational or irrational

Decision Making

Rational follows a defined reasoning process is driven by data/information

Irrational does not adhere to defined reasoning

process is not consistent with available data … or both

Decision Making

Rational decision making implies… there is a goal… the goal may be articulated as a set of

objectives… the objectives may explicate or implicate a set

of data elements that are relevant to achieving that objective

there is an identified reasoning process (formula, algorithm, procedure,…) for using the data elements to select the appropriate alternative.

can identify alternatives with values

Decision Making

Irrational decisions- using subjective factors or …undefined objectives using data outside the scope of the system does not follow defined reasoning processes

Will DSS users make irrational decision? yes

Will we, as DSS designers, support irrational decisions?

Decision Making

In the context of DSS – Decisions are usually made in sets –

part of a number of decisions made for a given situation

… sometimes these decisions are independent…

…sometimes they are interrelated. some decisions may be made in

juxtaposition to other decisions

Decision Theory

Please read the Introduction, SEU Theory and Limits of Human Rationality sections of the article by Herbert Simon at

http://dieoff.org/page163.htm

Decision TheoryChoice, Decision Making and Decision Theory - active area of research in psychology economics mathematics operations research political science Artificial Intelligence

the subject of Nobel Prizes

Decision Theory

SEU Theory – Subjective Expected Utility foundation for much work in

economics, operations research, etc. Utility maximizing Perfectly rational Assumes certainty, know probability

distributions, relevant information is available

Decision Theory

Limits of Rationality Why

How do we make decisions with limited rationality?Descriptive theories focus on how humans manage problems and make decisions with limited rationality

Decision Theory

What are the implications of limited rationality for the design of decision support systems?

Decision Support Design

You must- Properly frame the problem including-

identifying its components identifying its users

Describe the problem so someone else could build the system

Identify the decisions and alternatives Identify the data objects to support the

decisions Identify the data elements as components of the

data objects Identify the tools to support decision making

Software Engineering

just a bit

Software Design

How do we design software systems?Stare at the screen until it flows from our fingersGo out for a while, it might come to us later… there are better ways!

Software Design

Two types software design- Procedural design

focus on the algorithms data will be implied by the procedures

Object Oriented Design focus on the objects (what are objects?) data will be implied by the objects –

properties of the objects procedures are components of the

objects

Software Design

Bottom-up design start with a simple design, add complexity

Top-Down design Start with broad, comprehensive statement

of what the software/system is to do Successive refinement-

refine statement – explicit goals/objectives – major components/objects – data elements – procedures/methods

Think modules – create modules

Software Design

Components of Software Design User Definition Data Design – define data objects

Data Dictionary Architectural Design – the structural

definition of the system Module Interface Design – relationships

between program units Human Interface Design – how does it

look/act to the user Procedural Design – define the methods

Software Development Process – Major Steps

Feasibility/Utility AssessmentRequirements AnalysisDesignImplementationTestingDocumentation

Software Design

Some tools – UML Use Case models – represents actors in the

context of system functionality Object models – represents objects to be

included in the system – and the properties of these objects

Interface diagrams – show input and output interfaces

Others – sequence diagrams, state diagrams

Software Development Process

Waterfall model – successive stepsPrototyping model – build artificial system to define functionalityIncremental Model – design/build minimal system and add-onSpiral Model – continuous design, build, test, …