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AANNAALLYYSSIISS Chapter 19Chapter 19

Data Entry Procedures

Jerry Post

Copyright © 1997

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GoalsGoals

Collect accurate data. Effective data coding. Efficient data capture and

entry. Data validation.

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Data EncodingData Encoding

Simple ID Numbers Sequential

Easy to create. Problems if mistype by one

number.

Alphabetic Hide the count. Contain additional

information.

Classification codes e.g., M=male, F=female

Block sequence Sequential numbers

assigned to categories. 100-199 = spreadsheet 200-299 = database

Codes to conceal e.g., hide prices Simple substitution ciphers

(substitute one letter for a number, etc.)

Codes to provide information Categories (significant digit)

e.g., 2023954010 Dept. 202 Prod. 395 Color 40 Size 10

Mnemonic codes e.g., airports: STL, LAX,

SLC

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Guidelines for Creating CodesGuidelines for Creating Codes

Be concise. Keep the codes stable. Assure that codes are

unique. Allow codes to be sortable. Avoid confusing codes. Keep codes uniform. Allow for modification an

expansion. Make codes meaningful. Add check-digits.

Bad examples: 20927365123452 170AB, QQ9882, 2O008 Apr495, Mar396, Dec1595 1lS52ZO0

Better examples: 125, 998, 253 170AB, 982QQ, 291QB 950304, 960303, 951215

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Effective and Efficient Data CaptureEffective and Efficient Data Capture

Decide what to capture. Let the computer look up

data. Let the computer do

computations. Avoid bottlenecks and extra

steps. Start with a good form

(especially drop-down boxes).

Avoid batch data-entry. Collect data as close to the

source as possible.

Entry options Optical character

recognition (OCR). Magnetic ink character

recognition (MICR). Mark-sense forms. Punch-out forms. Bar codes. On-line/customer entry

(Web site).

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Data ValidationData Validation

Validating input transactions (errors to avoid). Submitting the wrong data. Submitting data by an

unauthorized person. Asking the system to

perform an unacceptable function.

Validating input data Test for missing data. Test for correct field length. Test for class or

composition. Test for range or

reasonableness. Test for invalid values. Test for comparison with

stored data. Design self-validating codes

(check digits).

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Check DigitsCheck Digits

Add a digit to the end of the code that is based on the earlier digits.

Need weights for each position. Catch transposition. Catch double errors.

Strongest is Cyclic Redundancy Check (CRC). Fits a polynomial to data. Catches most common

errors. Algorithm is in CS books.

Code: 54823Weights (1 x 3), Modulus: 105*1 = 54*3 = 128*1 = 82*3 = 63*1 = 3Add: 5 + 12 + 8 + 6 + 3 = 34Get modulus:34/10 = 3, remainder = 4(Optional: 10 - 4 = 6)New code: 548236