a) Before systems are put into organisational use, they should be well tested to ensure that the system being delivered is working as expected before it is implemented.
(i) What factors would determine the scope of system testing?
(ii) Who are involved in the testing process?
(iii) What do you consider to be limitations of software testing?
b) Decision support systems (DSS) are ISs that support managers in arriving at decisions in semi-structured problems. State any FOUR characteristics of DSS. Identify too the THREE main components of the DSS.
a) Software testing
i) The scope of the software test depends on:
Criticality of the system– if very critical would require thorough tests
Complexity (scope)- more complex more tests
Size of system- number of modules will dictate the duration and type of tests
Whether the system is stand alone or interfacing with other systems
ii) People involved in system testing
Operations manager/ management representative
iii) Limitations of software testing
Test data may not test all the possible types or values of data input that may occur within a system
There may be a problem of ensuring that all error messages contain adequate explanation to the errors that occur. Many error messages are quite understandable to the program writer but not necessarily to the program user-
e.g. error 43201 … may not be discernible for the user
The test plan may not cover all the functionality of the system especially if it is large and complex
Testing process may be inadequately documented- due to human error or lack of complete documentation
Inappropriate focus to the testing
The software may be tested to check what it should do rather than what it should not do
No good past experience for software testing (no rule of thumb)
Software is logical not physical thus it requires rational thinking
system testing can be complex and costly
Characteristics of DSS:
The DSS support managers in their work decision making. They overlay both data processing systems and office support systems and acquire their basic data from routine transaction processing
DSS have the following characteristics:
i) DSS are developed with the participation of and often, individual managers or a group of managers to support a range of decisions of concern to them.
ii) DSS directly support the decision making process. DSS are able to support unstructured problems where the manager interacting with the system supplies semi- structured decisions in which some of the dependencies between factors and their consequences are expressed models and some parts. Best suited for semi-structured problems where parts of the analysis can be computerised while still the decision marker‘s judgements and insight is needed to control the process. Tailoring to their needs.
iii) Provide analytical capabilities expressed in DSS models and this is the reason for the existence of these systems. This entails projecting possible future during a planning process. 2 principle modes of analysis are available. The
―what if ‖ mode, where the users consider alternative scenarios and their results and the goal seeking mode, the user asks, ―what would it take- in terms of input, factors to achieve a particular performance?‖
iv) In DSS, graphics are usually available to portray a decision situation made with a lot of scrutiny then it can be done with a tabular display of data.- graphical presentations
v) They combine internal and external information in supporting d-m.
vi) The computer provides support but does not replace the decision makers
(manager‘s) judgement. It doesn‘t provide pre-determined solutions.
vii) Common where effective problem solving is enhanced interaction between the computer and the manger.
1. The data management subsystem/ Database:
The data management subsystem of a DSS relies on a variety of internal and external databases. The power of DSS derives from their ability to provide easy access to data.
2. Model Management Subsystem/ Models:
The power of DSS pressed on the user ability to apply quantitative, mathematical models to data. Models have different areas of application and come from a variety of sources.
3. Dialogue Management Subsystem/ User Interface:
Along with DSS‘s ability to apply models to large volumes of data from a variety of sources, a single advantage of DSS is the user friendly and flexible interface between the decision-maker and such a system.