Information System Analysis

Topic 4

Information System Design

Output Design Objective \ Introduction

Output:

Information delivered to users through the information system by way of intranets, extranets, or the WWW

Many forms: hard copy (printed reports), soft copy (screens, microforms, audio)

Analyst works closely with user to develop output: after all, it’s FOR the user anyway

Output Design Objective

Output should be designed to:

  1. Serve the intended purpose
  2. During the information requirements determination phase of analysis, the systems analyst finds out what purposes must be served and then output is designed based on those purposes
  3. Design Output to Fit the User
  4. With many users, it’s hard to personalize output
  5. Try to design what many, if not all, users need and prefer
  6. Generally, it’s more practical to create user-specific or user customizable output when designing it for a DSS or other highly interactive applications such as those on the Web
  7. Designing the Appropriate Quantity of Output
  8. More is not always better
  9. Provide what each person needs to do his/her work
  10. Don’t overload just because the system can do it
  11. Users usually want great amounts of output at one time, especially when there’s an easy way to access more information
  12. Making Sure the Output is Where It’s Needed
  13. Make sure it gets presented to the right users
  14. Providing the Output on Time
  15. Could be daily, monthly, quarterly, annually, on exception, on demand
  16. Accurate timing is critical in some organizations
  17. Choosing the Right Output Method
  18. There are trade-offs for each method in terms of cost, accessibility, flexibility, life spans, distribution, storage and retrieval possibilities, transportability, and overall impact of the data

Designing Screen Output

–Output is ephemeral (not permanent like printed output)

–Users must be instructed on which keys to press to continue reading further screens and to interact with the display

–Access may be controlled via password; this is not done with printed output

Guidelines for Screen Design

–Keep the screen simple

–Keep the screen presentation consistent

–Facilitate user movement among screens

–Create an attractive screen

Input Design Objectives

–Ease of Use

–Effectiveness

–Accuracy

–Attractiveness

–Simplicity

–Consistency

Guidelines for Input Screen Design:

–Making Forms Easy to Fill In

–Meeting the Intended Purpose

–Assuring Accurate Completion

–Keeping Forms Attractive

Database Design

Designing data storage organization\ Objectives :

–Availability

–Integrity (accurate & consistent)

–Efficient storage of data as well as efficient updating and retrieval.

–The information retrieval be purposeful

There are two approaches to the storage of data in a computer system:

–Store the data in individual files each unique to a particular application.

–Store data in a computer-based system involves building a database.

Database:-

a database is a collection of non-redundant data which can be shared by different application systems

-Stresses the importance of multiple applications, data sharing

-Database becomes a common resource for an agency

Database:-

Changes can be made to data without affecting other components of the system

-change format of data items (real to integer, arithmetic operations)

-change file structure (reorganize data internally or change mode of access)

-relocate from one device to another, e.g. from optical to magnetic storage, from tape to disk

Objectives of Effective Databases:-

-Ensuring that data can be shared among users for a variety of applications.

-Maintaining data \accurate & consistent.

-Availability.

-Evolving the needs of the users to grow.

-Allowing users to construct their personal view of the data.

-Reduced cost of software development

-security restrictions

Database Design \ Normalization

A poor database design can cripple an application, producing problems with redundancy, inaccuracy, consistency, and concurrency of your data. Normalization is a process that serves to reduce, if not eliminate, these problems with data.

Normalization is the process of organizing data in the database

Redundant data wastes disk space and creates maintenance problems. If data that exists in more than one place must be changed, the data must be changed in exactly the same way in all locations which is time consuming and prone to errors.

Inconsistent dependency is a database design that makes certain assumptions about the location of data.

Inconsistent dependencies can make data difficult to access because the path to find the data may not be logical, or may be missing or broken.

The three steps of data normalization are:

  • Remove all repeating groups and identify the primary key.
  • Ensure that all nonkey attributes are fully dependent on the primary key.
  • Remove any transitive dependencies, attributes that are dependent on other nonkey attributes.

The process of normalization involves working through well-defined steps, called normal forms.

  1. First Normal Form (1NF)
  2. Second Normal Form (2NF)
  3. Third Normal Form (3NF)
  1. First Normal Form (1NF):
  2. A database is said to be in First Normal Form when all entities have a unique identifier or key, and when every column in every table contains only a single value and doesn't contain a repeating group or composite field
  1. Second Normal Form (2NF):
  2. A database is in Second Normal Form when it is in First Normal Form plus every non-primary key column in the table must depend on the entire primary key, not just part of it, assuming that the primary key is made up of composite columns.
  3. Third Normal Form (3NF)
  4. A database is in Third Normal Form when it is in Second Normal Form and each column that isn't part of the primary key doesn't depend on another column that isn't part of the primary key.

(Any Attribute depends on candidate key)

Additional normal forms have been defined, but are less commonly utilized. These advanced normal forms include Fourth Normal Form (4NF), Fifth Normal Form (5NF), Boyce Codd Normal Form (BCNF), and Domain-Key Normal Form (DK/NF).

Designing User Interface

The user interface is the system that helps users communicate with the computer system and/or the application system

User Interface Design Objectives:-

–Match the user interface to the task.

–Make the user interface efficient.

–Provide appropriate feedback to users.

–Generate usable queries.

–Improve productivity of knowledge workers.

Components of the User Interface:

–Presentation language, which is the computer-to-human part of the transaction.

–Action language that characterizes the human-to-computer portion.

Types of User Interfaces:

  1. Natural-language interfaces.

-Natural-language interfaces permit users to interact with the computer in their everyday or "natural" language.

  1. Question-and-answer interfaces.

-The computer displays a question for the user on the screen.

-The user enters an answer via the keyboard or a mouse click.

-The computer acts on that input information in a preprogrammed manner.

-New users may find the question-and-answer interface most comfortable.

  1. A menu interface.

-A menu interface, that provides the user with an screen list of available selections.

-A nested menu is a menu that can be reached through another menu.

  1. Form – Fill Interface

-Form-fill interfaces are onscreen forms displaying fields containing data items or parameters that need to be communicated to the user.

-Form-fill interfaces may be implemented using the Web.

  1. Command – Language Interfaces

-Allow the user to control the application with a series of keystrokes, commands, phrases, or some sequence of these.

-Require memorization of syntax rules.

-May be an obstacle for inexperienced users.