Systems analysis and design methods 7th whitten and benley chapter 12

Input Design and PrototypingMethods & Issues for Data Capture & Input  Data Capture, Data Entry, and Data Input  To input business data into a computer, the analyst may have to design

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Input Design and Prototyping

Introduction

 The chapter will address the following questions:

 What is the appropriate format and media for a computer input?

 What is the difference between data capture, data entry, and data input?

 Can you identify and describe several automatic data collection technologies?

 How do you apply human factors to the design of computer inputs?

 How do you design internal controls for computer inputs?

 How do you design a good source document for capturing

transaction data?

 How do you select proper screen-based controls for input attributes

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Methods & Issues for Data Capture

& Input

 Data Capture, Data Entry, and Data Input

 To input business data into a computer, the analyst may have to design source documents, input screens, and methods and procedures for

getting the data into the computer.

 Data accompanies business events called transactions.

 Systems analysts must determine when and how to capture the data.

 Data capture is the identification of new data to be input.

 It's always best to capture the data as soon as possible after it is originated.

 Traditionally, special paper forms called source documents were used

to capture the data.

 A source document is a paper form used to record data that will

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& Input

 Traditionally, special paper forms called source documents were used

to capture the data.

 A source document is a paper form used to record data that will

eventually be input to a computer

 With advances in video display technology, screen display forms are able to duplicate the appearance of almost any paper based form.

 Screen display forms and source documents must be designed to be easy for the system user to complete and should facilitate rapid

data entry.

• Data entry is the process of translating the source document into a

machine-readable format That format may be a magnetic disk, an

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& Input

 Data input is performed after data entry

format into the computer

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& Input

 Modern Input Methods: Batch versus On-Line Inputs

 Input methods can be broadly classified as either batch or on-line

Source documents or forms are collected and then periodically forwarded to data entry operators, who key the data using a data entry device that translates the data into a machine-readable format

 The most common medium for batch input data are

Key-to-disk (KTD) and key-to-tape (KTT) workstations that

transcribe data to magnetic disks and magnetic tape, respectively

•

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& Input

 Today, most, but not all, systems have been converted or are being converted to on-line methods

business and the direct inputting of that data to the computer, preferably as soon as possible after the data originates

 The on-line system includes a monitor screen and keyboard that are directly connected to a computer system

 Most new applications being developed today consists of screens having a “graphical” looking appearance called a

graphical user interface (GUI)

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& Input

 Today, most, but not all, systems have been converted or are being converted to on-line methods

processed in batches The data is input on-line with on-line editing Microcomputers or minicomputer systems can be used

to handle this on-line input and editing The data is not immediately processed Instead, it is batched, usually to some type of magnetic media At an appropriate time, the data is uploaded to the main computer, merged, and subsequently

processed as a batch Remote batch is also called deferred

batch or deferred processing.

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& Input

 Trends in Automatic Data Collection Technology

 Using today's technology, most if not all human intervention associated with the input methods previously discussed can be eliminated

 By eliminating human intervention, the time-delay and errors associated with human interaction can be decreased

 Biometric ADC systems consist of sensors that capture an individuals characteristic or trait, digitizes the image pattern, and then compares the image to stored patterns for

identification

 Biometric ADC are popular because they offer the most

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• The tag can be read by a reader whenever the object resides within

the electromagnetic field generated by the reader

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 MICR is most widely used in the banking industry

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& Input

 Trends in Automatic Data Collection Technology

 Bar coding is an example of optical technology

• Sophisticated laser readers read the bar code and send the data

represented by that code directly to the computer for processing

 The optical-mark form is another example of optical technology

• The source document becomes the input medium.

• The source document is directly read by an optical-mark reader

(OMR) or optical-character reader (OCR)

• The computer records the data to magnetic tape, which is then input

to the computer

• OCR and OMR input are generally suitable only for high-volume

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 Smart cards are similar, albeit slightly thicker, than credit cards

• They also differ in that they contain a microprocessor, memory

circuits, and a battery

• Smart cards are used on a daily basis by over 60% of the French

population

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& Input

 System User Issues for Input Design

 Inputs should be as simple as possible and designed to reduce the possibility of incorrect data being entered

 The following general principles should be followed for input design:

 Capture only variable data

 Do not capture data that can be calculated or stored in computer programs.

 Use codes for appropriate attributes

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& Input

 System User Issues for Input Design

 If source documents are used to capture data they should be easy for system users to complete and subsequently entered into the system

 The following suggestions may help:

 Include instructions for completing the form

 Minimize the amount of handwriting

 Data to be entered (keyed) should be sequenced so it can be read like this book, top to bottom and left to right

 Ideally, portions of the form that are not to be input are placed

in or about the lower right portion of the source document.

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xxxxx

xxxxxxxxxx xx-xx-xx xxxx

xxxx xxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

xxxx xxxxxxxxxxxxxxx xx x.xx xxx.xx next line xxxx xxxxxxxxxxxxxxx xx x.xx xxx.xx next line xxxx xxxxxxxxxxxxxxx xx x.xx xxx.xx next line xxxx xxxxxxxxxxxxxxx xx x.xx xxx.xx next line xxxx xxxxxxxxxxxxxxx xx x.xx xxx.xx next line xxxx xxxxxxxxxxxxxxx xx x.xx xxx.xx stop

xxxxx xxxxx xxxxxxxxxx xxxxxxxxxx xxxxx xxxxxxxxxx xx.xxx xx.xxx stop xx-xxx-xxx

Good

Bad

(a)

(b)

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& Input

 Internal Controls for Inputs

 Internal controls are a requirement in all computer-based systems

 Input controls ensure that the data input to the computer is

accurate and that the system is protected against accidental and intentional errors and abuse, including fraud

 The following internal control guidelines are offered for inputs:

 The number of inputs should be monitored

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& Input

 The following internal control guidelines are offered for inputs: (continued)

 Care must also be taken to ensure that the data is valid

• The following techniques are widely used to validate data:

– Completeness checks determine whether all required fields on

the input have actually been entered.

– Limit and range checks determine whether the input data for

each field falls within the legitimate set or range of values defined for that field

– Combination checks determine whether a known relationship

between two fields is valid

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& Input

 The following internal control guidelines are offered for inputs: (continued)

 Care must also be taken to ensure that the data is valid

• The following techniques are widely used to validate data:

(continued)

– Self-checking digits determine data entry errors on primary

keys (see following figure)

– Picture checks compare data entered against the known

COBOL picture or other language format defined for that data

 Data validation requires that special edit programs be written to perform checks

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MODULUS 11

The following procedure is used to assign a check digit to a key field:

STEP 1: Determine the size of the key field in digits.

12 + 20 + 4 + 9 + 10 = 55

STEP 5: Divide the sum from step 4 by 11.

55/11 = 5 Remainder 0 STEP 6: If the remainder is less than 10, append the remainder digit to the key field If

the remainder is equal to 10, append the character “X” to the key field.

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GUI Controls for Input Design

 Introduction

 Most new applications being developed today include a GUI

 This approach is influenced by a new trend in programming,

called repository-driven programming

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2

3

5 6 7

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 Text Box

 A text box consists of a rectangular shaped box that is usually

accompanied by a caption

 A text box requires the user to type the data inside the box

 A text box can allow for single or multiple lines of data characters

to entered

 When a text box contains multiple lines of data, scrolling features are also normally included

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 A text box is most appropriately used in those situations where the input data values are unlimited in scope and the analyst is unable to provide the user with a meaningful list of values from which they can select.

 A text box should be accompanied by a descriptive caption.

• Avoid using abbreviations for captions

• Only the first character of the caption’s text should be capitalized

• The caption should be located to left of the actual text box or left-aligned

immediately above the text box

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 Text Box

 The size of the text box should be large enough for all characters of fixed-length input data to be entered and viewed

by the user

• When the length of the data to be input is variable in length and

could become quite long, the text box’s scrolling and wrapping features should be applied

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word-Input Design and Prototyping

 When a choice is selected, any default or previously selected

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 Radio Button

 When a user is expected to input data that has a limited

predefined set of mutually exclusive values

 Radio buttons should present the alternatives vertically aligned and left-justified to aid the user in browsing

• The choices can be presented where they are aligned horizontally,

but adequate spacing should be used to help visually distinguish the choices

• The group of choices should be visually grouped to set them off from

other input controls appearing on the screen

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 Radio Button

 The sequencing of the choices should also be given consideration

 It is not recommended that radio button(s) be used to select the value for an input data whose value is simply a Yes/No (or

On/off state)

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 Check Box

 A check box also consists of two parts

 A square box followed by a textual description of the input field for which the user is to provide the Yes/No value

 Check boxes provide the user the flexibility of selecting the value via the keyboard or mouse

 An input data field whose value is “Yes” is represented by square that is filled with an “x”

 The absence of an “x” means the input field’s value is “No”

 The user simply toggles the input fields value from one value/state

to the other as desired

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 Check Box

 When a user needs to input a data field whose value set consists of a simple “Yes” or “No” value

 Make sure that the textual description is meaningful to the user

 Arrange the group of check box controls where they are aligned vertically and left-justified

• If necessary, align horizontally and be sure to leave adequate space

to visually separate the controls off from one another

 Appropriately sequence the input fields according to their

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 List Box

 A list box is a control that requires the user select a data item’s

value from a list of possible choices

 The list box is rectangular shaped and contains one or more rows

of possible data values

 The values may appear as either a textual description or graphical representation

 List boxes having a large number of possible values may consist of scroll bars to navigate through the row of choices

 A list box’s row may contain more than one column

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 When to Use List Boxes For Input:

 A list box’s scrolling capabilities make it appropriate for use in those cases where there is limited screen space available and the

input data item has a large number of predefined, mutually

exclusive set of values from which to choose

 Suggested Guidelines for Using List Boxes:

 A list box should be accompanied by a descriptive caption.

• Avoid using abbreviations for captions and capitalize only the first

character of the caption’s text

• The caption should be followed by a colon to help the user visually distinguish the caption from the box

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 List Box

 It is recommended that a list box contain a highlighted default value

 The width of the list box should be large enough for most characters of fixed-length input data to be entered and viewed

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