Designing Accurate
Data-Entry Procedures
Systems Analysis and Design
Kendall and Kendall
Major Topics
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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
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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 itself
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
magazine
Advantages of Alphabetic
Derivation Codes
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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
Classification Codes Problems
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
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
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
• 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
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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
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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
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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
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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
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