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MELJUN CORTES SAD ch15
 

MELJUN CORTES SAD ch15

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MELJUN CORTES SAD ch15

MELJUN CORTES SAD ch15

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    MELJUN CORTES SAD ch15 MELJUN CORTES SAD ch15 Presentation Transcript

    • Chapter 15Designing AccurateData-Entry Procedures Systems Analysis and DesignMELJUN CORTES
    • Major Topics • Data entry • Effective coding • Types of codes • Guidelines for coding • Validation methods • Check digits • Ecommerce accuracyKendall & 2005 PearsonKendall Prentice Hall 15-2
    • 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.Kendall & 2005 PearsonKendall Prentice Hall 15-3
    • 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.Kendall & 2005 PearsonKendall Prentice Hall 15-4
    • Purpose of Coding Besides providing accuracy and efficiency, coding does the following: • Keeps track of something. • Classifies information. • Conceals information. • Reveals information. • Requests appropriate action.Kendall & 2005 PearsonKendall Prentice Hall 15-5
    • 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.Kendall & 2005 PearsonKendall Prentice Hall 15-6
    • Simple Sequence Code • Identifies 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 • No relation to the data itselfKendall & 2005 PearsonKendall Prentice Hall 15-7
    • Alphabetic Derivation Codes • A commonly used approach in identifying an account number • See figure 15.2, for example, where the code becomes the account numberKendall & 2005 PearsonKendall Prentice Hall 15-8
    • Alphabetic Derivation Codes(Continued) • First five digits come from the first five digits of the subscribers zip code. • Next three are the first three consonants in the subscribers name. • Next four numbers are the street address. • Last three make up the code for the magazine.Code Format of Code68506KND7533TVG 99999XXX9999XXXKendall & 2005 PearsonKendall Prentice Hall 15-9
    • Advantages of AlphabeticDerivation Codes Advantages are: • 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.Kendall & 2005 PearsonKendall Prentice Hall 15-10
    • Disadvantages of AlphabeticDerivation Codes Disadvantages are: • 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.Kendall & 2005 PearsonKendall Prentice Hall 15-11
    • Classification Information • Coding affords the ability to distinguish between classes of items. • Classes must be mutually exclusive. • Classification Codes are used to distinguish one group of data with special characteristics from anotherKendall & 2005 PearsonKendall Prentice Hall 15-12
    • Classification Information(Continued) • They consist of either a single letter or a number. • Codes are shorthand way of describing a person, place, thing, or event. • Classification codes are listed in manuals or posted so that users can locate them easily.Kendall & 2005 PearsonKendall Prentice Hall 15-13
    • Classification Codes • Use a single letter for a code.Kendall & 2005 PearsonKendall Prentice Hall 15-14
    • Classification Codes ProblemsKendall & 2005 PearsonKendall Prentice Hall 15-15
    • Block Sequence Codes • An extension of the sequence code • Advantages • Data are grouped according to common characteristics • Simplicity of assigning the next available number (within the block) to the next item needing identification • Can do inquiries on code beginningsKendall & 2005 PearsonKendall Prentice Hall 15-16
    • Block Sequence CodeKendall & 2005 PearsonKendall Prentice Hall 15-17
    • Cipher Codes • Codes may be used to conceal or disguise information. • Cipher Codes is the direct substitution of one letter for another, one number for another, or one letter for a number.Kendall & 2005 PearsonKendall Prentice Hall 15-18
    • Cipher Codes Code Meaning B 1 Style Code L 2 E 3 GOLDEN’S A 4 202-395-40 C 5 BIMC H 6 M 7 Size 12 I 8 $25.00 N 9Kendall & D 0 2005 PearsonKendall Prentice Hall 15-19
    • 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.Kendall & 2005 PearsonKendall Prentice Hall 15-20
    • 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.Kendall & 2005 PearsonKendall Prentice Hall 15-21
    • Significant Digit Subsets(Continued)• Can do inquiries on portions of the code. • Look for matching red items, other size 10 items, other maternity, or similar dresses Code Merchandise Described 2023954010 Red maternity dress, style 395, size 10 202 Department (maternity) 395 Product (dress style 395) 40 Color (red)KendallSize (size=10) Pearson 10 & 2005Kendall Prentice Hall 15-22
    • 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 is mnemomic. • Using a combination of letters and symbols affords a clear way to code a product so that the code is easily seen and understood.Kendall & 2005 PearsonKendall Prentice Hall 15-23
    • Unicode • Unicode is used to store glyphs or symbols representing syllables or whole words. • Used for languages that are not Western alphabetic (Latin characters) • Stores 65,535 characters • Viewed using an input method editor • Represented using the &#hhhh where hhhh represents hexadecimal notation • Example: &3x3053 for the Japanese syllable koKendall & 2005 PearsonKendall Prentice Hall 15-24
    • Function Codes • Codes are often necessary for instructing either the computer or the person about actions to take. • Function codes are short numerical or alphabetic codes used to spell out precisely what activities are to be accomplished.Kendall & 2005 PearsonKendall Prentice Hall 15-25
    • Guidelines for Coding • Guidelines for coding are: • 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.Kendall & 2005 PearsonKendall Prentice Hall 15-26
    • 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.Kendall & 2005 PearsonKendall Prentice Hall 15-27
    • Keep Codes Stable Stability means that the identification code for a customer should not change each time new data are received.Kendall & 2005 PearsonKendall Prentice Hall 15-28
    • Make Codes That are Unique • Codes should be unique. • Make a note of all codes used in the system. • Do not assign the same code number or name to the same items.Kendall & 2005 PearsonKendall Prentice Hall 15-29
    • Allow Codes to be Sortable • Codes must be sortable. • For example: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 dataKendall & 2005 PearsonKendall Prentice Hall 15-30
    • 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.Kendall & The code format is X9X 9X9. • 2005 PearsonKendall Prentice Hall 15-31
    • 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 - centuryKendall & 2005 PearsonKendall Prentice Hall 15-32
    • Allow for Modification of Codes • The system will evolve over time. • The coding system should be able to encompass change.Kendall & 2005 PearsonKendall Prentice Hall 15-33
    • 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.Kendall & 2005 PearsonKendall Prentice Hall 15-34
    • 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.Kendall & 2005 PearsonKendall Prentice Hall 15-35
    • Effective Data Capture In order to assure the quality of data entered into the system, it is important to capture data effectively.Kendall & 2005 PearsonKendall Prentice Hall 15-36
    • Guidelines for Effective DataCapture Guidelines for effective and efficient data capture are: • 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.Kendall & 2005 PearsonKendall Prentice Hall 15-37
    • Data-Entry Methods Data-entry methods include: • Keyboards. • Optical character recognition. • Magnetic ink character recognition. • Mark-sense forms. • Bar codes. • Intelligent terminals.Kendall & 2005 PearsonKendall Prentice Hall 15-38
    • Bar Code ExampleKendall & 2005 PearsonKendall Prentice Hall 15-39
    • 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.Kendall & 2005 PearsonKendall Prentice Hall 15-40
    • 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.Kendall & 2005 PearsonKendall Prentice Hall 15-41
    • 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.Kendall & 2005 PearsonKendall Prentice Hall 15-42
    • 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.Kendall & 2005 PearsonKendall Prentice Hall 15-43
    • Check Digits (Continued) • 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 methodKendall & 2005 PearsonKendall Prentice Hall 15-44
    • 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.Kendall & 2005 PearsonKendall Prentice Hall 15-45
    • Check Digit General MethodRemaining 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.Kendall & 2005 PearsonKendall Prentice Hall 15-46
    • Modulus 11 Arithmetic Method Number 2 9 6 4 5 Original number Weights 6 5 4 3 2 29645 Product 12 45 24 12 10 Sum of products = 103 Final number Divide 103/11 = 9 remainder 4 296457 Checkdigit = 11- 4 = 7 9R4 11 11 103 - 4 -99 7Kendall & 4 Pearson 2005Kendall Prentice Hall 15-47
    • The Process of Validation • Check first for missing data. • Then check the syntax: the length, class, and composition. • Next check the semantics: the meaning of the data: • Limit. • Range. • Check digit.Kendall & 2005 PearsonKendall Prentice Hall 15-48
    • Regular Expressions • Use a pattern for validation. • Symbols represent the type of data. • Example: Email validation. [A-Za-z0-9]w{2,}@[A-Za-z0-9]w{3,}.[A-Za-z]{3}/Kendall & 2005 PearsonKendall Prentice Hall 15-49
    • Regular Expression CodesKendall & 2005 PearsonKendall Prentice Hall 15-50
    • 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.Kendall & 2005 PearsonKendall Prentice Hall 15-51