Aug 1997 IM218: Information Management (Question 5) Suggested Solutions

5.	Performance evaluation and maintenance are essential aspects of systems management.
	(a) Explain exactly what is meant by performance evaluation.		[2]
	Performance evaluation is the systematic determination (or measurement) of the productivity (or effectiveness, or efficiency) of an object, a piece of hardware or software.
	[2 marks]
	one mark for measurement, one mark for productivity

	(b) Describe the process of performance evaluation, explaining what is involved at each step.		[8]
	The process of performance evaluation involves the identification		[1]
	of critical components or properties		[1]
	and the production of an inventory		[1]
	up to a maximum of 2 marks for this part of the process
	It involves the production of a model		[1]
	to describe how the system operates; the model simulates		[1]
	the system in terms of the effects of input, output, and environmental conditions; casual relationships may be proposed.		[1]
	This model must be validated for accuracy; model validation involves determining whether or not the outputs of the actual system are approximated or predicted correctly by those of the model.		[1]
	up to a maximum of 2 marks for this part of the process
	The model is then used to predict		[1]
	the behaviour of the system under changed conditions; the effects of change are examined using the model.		[1]
	This information is used to identify the best solution:		[1]
	the change that appears to offer the most benefit when all identified factors are considered. The choice of change may depend upon the cost of the change as well as the nature of the final result.		[1]
	up to a maximum of 2 marks for this part of the process
	The system is then changed.		[1]
	The changed system is monitored		[1]
	to confirm that the predicted benefits have been obtained. If this is not the case, then it may be necessary to begin the process again, or to retract the changes and modify the model.		[1]
	up to a maximum of 2 marks for this part of the process
	[8 marks]

	(c) Suggest two ways in which we can reduce the cost of software maintenance.		[2]
	The cost of software maintenance can be reduced by improving the quality of software development,		[1]
	using techniques such as structured and object-oriented programming,		[1]
	and employing tools such as code generators and re-structuring engines		[1]
	up to a maximum of 2 marks
	[2 marks]

	(d) Identify and describe four types of, or approaches to, system maintenance.		[8]
	*The four* types of, or approaches to, system maintenance are:**
		corrective maintenance:	[1]
		correcting errors once problems have become apparent, or once problems have occurred	[1]
		adaptive maintenance:	[1]
		in response to changes in requirements	[1]
		perfective maintenance:	[1]
		enhancing the system in some way:	[1]
		performance, efficiency, maintainability
		preventative maintenance:	[1]
		periodic inspection and review to uncover and anticipate problems	[1]
	[8 marks]