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, …
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