Software Evaluation

Catherine McKeveney

Medical Informatics

1st March 2000

Software Life Cycle

Software Engineering Software Development Software Evaluation

Software Engineering

Software engineering is the systematic approach to the development, operation, maintenance and retirement of software.

The inability of organisations to predict time, effort and cost in software development and the poor quality of the software that was produced, were only two of the driving forces behind the emergence of software engineering as a discipline.

Quality Software: Reliability

low costs

Increased Productivity

Flexibility

Functionality

Ease of Learning

Ease of Remembering

Ease of Use

Mininum Errors

Good Documentation

Readable CodeGood Design

SPONSOR USER

MAINTAINER

What is Required by Whom?

Sponser : value for £‘s User: carries out functions Maintainer: few errors

EVERYONE: RELIABILITY

Software Development Cycle

Requirements analysis and specification Design Implementation System testing Installation

Costs of Software Development

Ownership Costs 67%

Development Costs33%

Communication!

The sponsor has a general idea of what he or she wants the program to do, but may not really understand how computers work or what is involved in programming.

The programmer, on the other hand, knows a lot about computers and programming, but typically does not know very much about the task from the sponsors point of view.

Requirements Analysis

A contract between sponsor and developers Addresses the following questions:

– Who– What– When– Where– Why

Requirements Decisions Functional

– relate directly to the functioning or operations of the system

Non-functional– User Interface and human factors– Hardware considerations– Performance characteristics– Error handling and extreme conditions– Quality issues

User Interface Quality

Ease of learning Speed of use Frequency of user errors User satisfaction Knowledge retention

Interaction Styles

Menu Selection Form fill-in Command Language Direct Manipulation

Rules for Interface Design

Strive for consistency Enable frequent users to use shortcuts Offer informative feedback Permit easy reversal of actions

Training and Help!

Training manuals On-line Help Meaningful error messages

Evaluation Summary

Functionality Interface Ease of Use Speed Who uses it Manuals/Online help