Chapter 19 Designing Accurate Data-Entry Procedures Systems Analysis and Design Kendall and Kendall Fifth Edition

Chapter 19Designing AccurateData-Entry Procedures

Systems Analysis and DesignKendall and Kendall

Fifth Edition

Kendall & Kendall Copyright © 2002 by Prentice Hall, Inc. 19-2

Major Topics

Data entry Effective coding Types of codes Guidelines for coding Validation methods Check digits Ecommerce accuracy


Quality Data-Entry Objectives

The quality of data input determines the quality of information output

Accurate data entry is achieved through four broad objectives:

Effective coding Effective data capture Efficient data capture and entry Assuring quality through validation


Codes and Coding

Coding helps efficiency because Data that are coded require less time to

enter Coding helps to reduce the number of

items entered Coding can help in sorting of data during

the data transformation process Coded data can save valuable

memory/storage space


Purpose of Coding

Besides providing accuracy and efficiency, coding does the following: Keeping track of something Classifying information Concealing information Revealing information Requesting appropriate action


Types of Codes Types of codes are

Simple sequence code Alphabetic derivation codes Classification codes Block sequence codes Cipher codes Significant digit subsets Mnemonic codes Function codes


Simple Sequence Code

Identify a person, place, or thing in order to keep track of it

A number that is assigned to something if it needs to be numbered

It has no relation to the data itselfOrder Number Product5676 Rocking Chair5677 Dining Room Table5678 Love Seat


Alphabetic Derivation Codes

A commonly used approach in identifying an account number

The code becomes the account number


Alphabetic Derivation Codes

First five digits come from the first five digits of the subscriber's zip code

Next three are the first three consonants in the subscriber's name

Next four numbers are the street address Last three make up the code for the

magazineCode Format of Code68506KND7533TVG 99999XXX9999XXX


Advantages of Alphabetic Derivation Codes

Advantages Can have zip code in front for sorting A requirement for bulk mailing A magazine subscription may be used

weekly for mailing Can verify a person calling about their

account


Disadvantages of Alphabetic Derivation Codes

Disadvantages Names like ROE - become RXX Street addresses like 12 OAK STREET

- code contains 1200 Changing name or address results in

the key field being changed


Classification Information

Coding affords the ability to distinguish between classes of items

Classes must be mutually exclusive Classification Codes Used to distinguish one group of data

with special characteristics from another


Classification Information

Consist of either a single letter or a number

A shorthand way of describing a person, place, thing, or happening

Classification codes are listed in manuals or posted so that users can locate them easily


Classification Codes

Use a single letter for a code

Code Tax Deductible ItemInterest Payments

Medical Payments Taxes Contributions Dues

Supplies

IMTCDS


Classification Codes Problems

Code Tax Deductible ItemInterest Payments

Medical Payments Taxes Contributions Dues

Supplies Subscriptions Computer Insurance Miscellaneous

IMTCDSBPNX


Block Sequence Codes

An extension of the sequence code Advantages

That the data are grouped according to common characteristics

The simplicity of assigning the next available number (within the block) to the next item needing identification

Can do inquiries on code beginnings


Block Sequence Code

Code Name of Software Package Type100 Netscape Browser101 Internet Explorer102 Lynx200 Access Database201 Paradox202 Oracle300 Word Word Processing301 WordPerfect400 Astound Presentation401 Micrograf Designer


Cipher Codes

Codes may be used to conceal or disguise information

Cipher Codes Direct substitution of one letter for

another, one number for another, or one letter for a number


Cipher Codes

Code Meaning B 1 L 2 E 3 A 4 C 5 H 6 M 7 I 8 N 9 D 0

GOLDEN’S202-395-40BIMC

Size 12$25.00

Style Code


Revealing Information

Sometimes it is desirable to reveal information through a code

Make the data entry more meaningful

Allows persons to view the code and understand what it means


Significant Digit Subsets

Used to describe a product via its membership in many subgroups

The advantage of using a significant-digit subset code is the ability to locate items that belong to a certain group or class


Significant Digit Subsets

Code Merchandise Described2023954010 Red maternity dress, style 395, size 10

202 Department (maternity)395 Product (dress style 395)40 Color (red)10 Size (size=10)

Can do inquiries on portions of the code Look for matching red items, other size

10 items, other maternity, or similar dresses


Mnemonic Codes

A mnemonic (pronounced nî-môn'-ïk) is a memory aid

Any code that helps data-entry person remember how to enter the data or

End user remember how to use the information

Uses a combination of letters and symbols


Function Codes

Codes are often necessary for instructing either the computer or the person about actions to take

Function Codes Spelling out precisely what

activities are to be accomplished is replaced by the use of a short numerical or alphabetic code


Guidelines for Coding

Guidelines for coding Keep codes concise Keep codes stable Make codes that are unique Allow codes to be sortable Avoid confusing codes Keep codes uniform Allow for modification of codes Make codes meaningful


Keep Codes Concise

Overly long codes mean more keystrokes and consequently more errors

Long codes also mean the information in the files will require more memory

If codes must be long, they should be broken up into subcodes


Keep Codes Stable

Stability means that the identification code for a customer should not change each time new data are received


Make Codes That are Unique

Assure that codes are unique Make a note of all codes used in

the system Do not assign the same code

number or name to the same items


Allow Codes to be Sortable

The codes must be sortable Problem date: MMMDDYY

First three symbols are the month as a three-letter abbreviation

Second two are the date as a number Last two digits are the year

Numerical codes are much easier to sort than alpha-numeric data


Avoid Confusing Codes

Avoid using coding characters that look or sound alike O (the letter oh) and 0 (the number zero) Letter I and the number 1 Letter Z and the number 2 Codes such as B1C and 280Z are

confusing Canadian Postal Code The code format is X9X 9X9


Keep Codes Uniform

Follow readily perceived forms most of the time Avoid using the codes MMDDYY in one

application YYDDMM in a second MMDDCCYY in a third; CC - century


Allow for Modification of Codes

The system will evolve over time The coding system should be able

to encompass change


Make Codes Meaningful

Effective codes contain information They should make sense to people

using them Meaningful codes are easier to

understand, work with, and recall


Using Codes

Codes are used In validation programs to ensure that only

valid codes have been entered In report and inquiry programs to display

code meanings In GUI programs to create drop-down lists This helps to ensure accurate data, since

the user sees the code and it’s meaning and can only select a code from the list


Effective Data Capture

In order to assure the quality of data entered into the system, it is important to capture data effectively


Guidelines for Effective Data Capture

Guidelines for effective and efficient data capture Deciding what to capture Letting the computer do the rest Avoiding bottlenecks and extra steps Starting with a good form Choosing a data-entry method


Validation Overview

To assure data quality, errors should be detected during input, prior to processing and storage

Two possible ways to validate inputs are: Validation of input transactions Validation of input data


Data-Entry Methods

Data-entry methods include Keyboards Optical character recognition Magnetic ink character recognition Mark-sense forms Bar codes Intelligent terminals


Problems With Input Data

Three main problems that can occur with input transactions are Submitting the wrong data to the

system Submitting of data by an

unauthorized person Asking the system to perform an

unacceptable function


Validation Methods

Validation methods include Test for missing data Test for correct field length Test for class or composition Test for range or reasonableness Test for invalid values Cross-reference checks Test for comparison with stored data


Check Digits

Check digits are used to validate a numeric field by performing a calculation on a part of the number and comparing the result with a digit stored within the number

Check digits help to detect Single digit miskey Transposition errors


Check Digits

There are several check digit methods: Modulus 10, “2-1-2” method Modulus 10, “3-1-3” method Modulus 11, arithmetic method Modulus 11, geometric method


Check Digit General Method

Start with the numeric code Choose the weighting method and

modulus number Multiply the digit by the chosen

weight Sum the new numbers Divide by the modulus number


Check Digit General Method Remaining Steps

Compute the check digit by taking the modulus number and subtracting the remainder Subtract again if greater than 10

Add check digit to the end of the number

Use this new code for data entry and let the computer validate the code


Modulus 11 Arithmetic Method

Number 2 9 6 4 5 Original numberWeights 6 5 4 3 2 29645Product 12 45 24 12 10

Sum of products = 103 Final numberDivide 103/11 = 9 remainder 4 296457Checkdigit = 11- 4 = 7

11 - 4 7

9 R 411 103

-994


Using Codes

Codes may be included in drop-down lists when using a GUI interface

This helps to ensure that the data entered are accurate, since the user sees both the code and it’s meaning and can only select a code from the list


Ecommerce Accuracy

Ecommerce environments have increased accuracy of data because Customers generally enter data themselves Data entered by customers are stored for

later use Data entered at the point of sale are used

throughout the order fulfillment process Information is used as feedback to customers

Documents

Chapter 19 Designing Accurate Data-Entry Procedures Systems Analysis and Design Kendall and Kendall Fifth Edition