Describe the habits of successful interface designers

CHAPTER 8 User Interface Design

Chapter 8 is the first of three chapters in the systems design phase of the SDLC. This chapter explains how to design an effective user interface, and how to handle data security and control issues. The chapter stresses the importance of user feedback and involvement in all design decisions.

OBJECTIVES

When you finish this chapter, you will be able to :

· Explain the concept of user interface design and human-computer interaction, including basic principles of user-centered design

· Explain how experienced interface designers perform their tasks

· Describe rules for successful interface design

· Discuss input and output technology issues

· Design effective source documents and forms

· Explain printed output guidelines

· Describe output and input controls and security

· Explain modular design and prototyping techniques

INTRODUCTION

User interface design is the first task in the systems design phase of the SDLC. Designing the interface is extremely important because everyone wants a system that is easy to learn and use.

After discussing the user interface, human-computer interaction, and interface design rules, the chapter describes output, data security and control issues, prototyping, and the next steps in the systems design process.

PREVIEW CASE: Mountain View College Bookstore

Background: Wendy Lee, manager of college services at Mountain View College, wants a new information system that will improve efficiency and customer service at the three college bookstores.

In this part of the case, Tina Allen (systems analyst) and David Conroe (student intern) are talking about user interface design issues.

Participants:

Tina and David

Location:

Mountain View College Cafeteria, Monday afternoon, November 25, 2013

Project status:

Tina and David have examined development strategies for the new bookstore system. After performing cost-benefit analysis, they recommended in-house development of the new bookstore system. Now they are ready to begin the systems design phase by working on user interface design for the new system.

Discussion topics:

User interface design concepts and principles

Tina:

Hi, David. Ready to start work on user interface design?

David:

Sure. Will we start with output because it’s important to users?

Tina:

Output is very important, but the most important issue for users is the interface itself. For example, is it easy to learn? Is it easy to work with? We’ll try to design everything — output, input, and all the other elements — from a user’s point of view.

David:

How do we do that?

Tina:

Well, many sources of information about effective design concepts and principles are available. We’ll study those, and then ask our own users for their input and suggestions.

David:

What about input and data entry?

Tina:

Good question, You’ve heard the old saying, “garbage in, garbage out.” User interface principles apply to user input generally, but repetitive data entry deserves special attention. We need to create screen forms that are logical and easy to understand, as well as input masks and data entry validation rules. We also need to review any source documents that will be filled in manually.

David:

Anything else?

Tina:

Yes. The bookstore system probably will have some confidential data regarding budgets and markup policies, so we’ll have to consider security and control issues. If you’re ready, here’s a task list to get us started:

FIGURE 8-1 Typical user interface design tasks.

© Cengage Learning 2014

SYSTEMS DESIGN PHASE OVERVIEW

Because the components of a system are interdependent, the design phase is not a series of clearly defined steps. Although you might start in one area, you could find yourself working with several different elements at the same time. For example, a decision to change a report format might require changes in data design or input screens. Your design checklist will include the user interface, input and output procedures, data design, and system architecture. At the end of this phase, you will prepare a systems design specification and deliver a presentation to management.

The goal of systems design is to build a system that is effective, reliable, and maintainable.

· A system is reliable if it handles input errors, processing errors, hardware failures, or human mistakes. A good design will anticipate errors, detect them as early as possible, make it easy to correct them, and prevent them from damaging the system itself.

· A system is maintainable if it is flexible, scalable, and easily modified. Changes might be needed to correct problems, adapt to user requirements, or take advantage of new technology.

· A system is effective if it supports business requirements and meets user needs.

Although each project is different, the following basic principles usually apply.

Will It Succeed?

A system might have advanced technology and powerful features, but the real test is whether users like it and feel that it meets their needs. Here are some suggestions for successful design:

· Think like a user. Carefully examine any point where users provide input or receive output. The user interface must be easy to learn. Input processes should be easy to follow, intuitive, and forgiving of errors. Predesigned output should be attractive and easy to understand, with an appropriate level of detail.

· Anticipate future needs. Consider a parts inventory database that contains a one-character field for category, such as electrical, mechanical, or hydraulic. The design works well, but what if the company decides to break these overall groups down into more specific segments? A better design would anticipate possible expansion to two or more characters. For example, in 1999, there was widespread concern about what was called the Y2K issue because many older programs used only two characters to store the year, and might not recognize the start of a new century.

· Provide flexibility. Suppose that a user wants a screen display of all customer balances that exceed $5,000 in an accounts receivable system. How should you design that feature? The program could be coded to check customer balances against a fixed value of 5000, which is a simple solution for both the programmer and the user because no extra keystrokes are required to produce the display. However, that approach is inflexible. A better approach would be to let the user enter the amount. Or you could start with a default value that displays automatically. Users can press ENTER to accept the value, or type in another value. Often the best design strategy is to offer several alternatives, so users can decide what will work best for them.

· Manage data effectively. In addition to its effect on users, data management impacts company efficiency, productivity, and security. To reduce input errors, the system should enter and verify data as soon as possible, and each data item should have a specific type, such as alphabetic, numeric, or alphanumeric, and a range of acceptable values.

It is important to collect input data as close to its source as possible. For instance, using barcode scanners rather than manual forms on a warehouse freight dock, or having salespeople use tablets to record orders rather than filling in source documents. The easiest, most accurate, and least expensive data input strategy is automated data capture, such as the RFID scanner shown in Figure 8-2 .

In an efficient design, data is entered only once. For example, if input data for a payroll system also is needed for a human resources system, you can either design an interface to transfer data automatically, or create a central data storage area that both systems can access. In Chapter 9 , you will learn about normalization, which is a set of rules that can help you avoid data design problems. A secure system also includes audit trails that can log every instance of data entry and changes. For example, the system should record when a customer’s credit limit was set, by whom, and any other information necessary to construct the history of a transaction.