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

2. Copyright © 2002 by Prentice Hall, Inc.
Major Topics
Data entry
Effective coding
Types of codes
Guidelines for coding
Validation methods
Check digits
Ecommerce accuracy
Kendall & Kendall
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3. 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
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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
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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
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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
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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 itself
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8. Alphabetic Derivation Codes
A commonly used approach in identifying an account number
The code becomes the account number
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9. 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 magazine
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10. Advantages of Alphabetic Derivation Codes
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
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11. Disadvantages of Alphabetic Derivation Codes
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
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12. 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
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13. 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
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Classification Codes
Use a single letter for a code
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15. Classification Codes Problems
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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
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Block Sequence Code
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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
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Cipher Codes
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20. 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
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21. 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
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22. Significant Digit Subsets
Can do inquiries on portions of the code
Look for matching red items, other size 10 items, other maternity, or similar dresses
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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
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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
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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
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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
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Keep Codes Stable
Stability means that the identification code for a customer should not change each time new data are received
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28. 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
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29. 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
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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
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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
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32. Allow for Modification of Codes
The system will evolve over time
The coding system should be able to encompass change
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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
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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
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35. Effective Data Capture
In order to assure the quality of data entered into the system, it is important to capture data effectively
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36. 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
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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
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Data-Entry Methods
Data-entry methods include
Keyboards
Optical character recognition
Magnetic ink character recognition
Mark-sense forms
Bar codes
Intelligent terminals
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39. 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
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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
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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
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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
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43. 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
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44. 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
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45. Modulus 11 Arithmetic Method
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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
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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
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