Technology-
related contex
User-related
contex
Security
Connectivity
Synergy
User’s Decision
Model
Historical
context
Completeness
Currency
D
Accuracy
3 STATIC AND DYNAMIC
DECISION MAKING
Much of our previous work using MCDA has
adopted the approach in static decision making. In
static decision making, we can assume that the
evaluation of alternatives with respect to criteria is
constant (over a given period of time), and
evaluations will not fluctuate according to some
external factor. For example, in assessing a suitable
location to conduct a conference, criteria such as
size of rooms, facilities available, and
accommodation costs will have scores that are
unlikely to change from one minute to the next, one
day to the next, or even one week to the next.
There are however some genres of problems
which encompass dynamic as well as static criteria.
For example, suppose we are considering the best
mode of transport to our work place. Travel time is
a very dynamic attribute in that it can change
frequently. We may have an idea of approximate
travel times for different modes of transport (e.g.
train, bus, car), however, this information may
change after listening to travel reports on the radio
prior to setting off for work, causing us to re-rank
which mode of transport will get us to work in the
shortest time. This scenario is still not static, as 5
minutes into our journey the travel situation may
change again, such that perhaps a different mode of
transport would have been preferable. In such
situations, it is important to have some indication of
how static or dynamic our decision is, and some
estimation of the time period over which the stability
of the data is likely to be maintained. So for
example, if we choose to travel by train as it is
currently the best option, is it likely that this will
remain the optimum option for a given time period,
say 30 minutes. It is here we see the need to not
only provide decision support in the more traditional
sense as seen with static decisions, but also to give
some indication of the quality of the decision or
quality of data being received.
4 QUALITY OF DATA
Our measure of quality is not reflective of the
standard of the information received, but of the
robustness, recency, and stability of the data. Recent
research defines QoD as a score that allows the user
to appreciate the uncertainties inherent to a mobile
computing environment (Mihaila et al, 2000). By
using QoD, appropriate sensitivity analysis can be
performed and results used to better inform the user
as to the suitability of choices. This additional
information allows the decision maker to make their
decision with confidence as not only are they
presented with the pertinent data, they are also aware
of changes in the environment and the potential
impact this could have on the decisions made.
Figure 1: Quality of Data Model.
In Figure 1 we illustrate how QoD can be
represented as an aggregate measure of technology-
related parameters (e.g., synergy, security and
connectivity), user-related parameters (e.g., stability
of scores in user’s decision model), and data quality
parameters that are related to historical context (e.g.,
completeness, currency and accuracy of historical
data). This aggregate measure can be represented as
a weighted sum, to allow the decision maker to
choose the importance associated with the various
quality measures. Further details of the QoD
measure can be found in Cowie and Burstein (2006).
5 THE PROTOTYPE
5.1 Setting Up the Model
The prototype was developed using an Object
Oriented (OO) methodology, where unified
modelling language (UML) was used to assist in
conceptualising the design of the prototype.
Although the Decision Support System (DSS)
proposed is designed to operate on a number of
mobile devices, this initial design is for use on a
PDA. The technologies used comprised of Java ME,
Java SE, Excel, MySQL and the multicriteria
decision analysis software V•I•S•A.
In order to use the prototype, an appropriate
MCDA model must be created and imported onto
the mobile decision device (such as a PDA).
Through access to the web, the PDA can then keep
the decision maker up-to-date with the latest
information pertinent to the problem domain being
addressed.
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