Computer Basics

3 - Input: Data Accuracy

A famous slogan in computing sums up the importance of accurate data:

GIGO = Garbage In, Garbage Out

Garbage In, Garbage Out

Conclusions are no better than the data they are based on.

Checking for Accuracy

A major task for any program that accepts data is to try to guarantee the accuracy of the input. Some kinds of errors cannot be caught but many of the most common kinds of mistakes can be spotted by a well-designed program.

A program should attempt to do the following:

1.	test data type and format	ex.	2/a/96 is not a date
		ex.	If a phone number should have exactly 10 digits with the area code, then 555-123 is not acceptable.
2.	test data reasonableness	ex.	231 should not be a person's age
		ex.	A sale of $50,000 worth of chewing gum at the corner market is probably missing a decimal point somewhere!
3.	test data consistency	ex.	A man's death date should be later than his birth date!
		ex.	The sum of the monthly paychecks should be the same as the total pay for the year.
4.	test for transcription and transposition errors	ex.	Typing 7754 instead of 7154 is a transcription error, typing the wrong character.
		ex.	Typing 7754 instead of 7745 is a transposition error, interchanging two correct characters. Both are very hard to check for.

Where you are: JegsWorks > Lessons > Computer Basics
	1. Computer Types
	2. Applications
	3. Input Intro Keyboard: framed no frames Pointing Devices Terminals Multimedia Data Automation Data Accuracy Quiz
	4. Processing
	5. Output
	6. Storage
	7. Computer to Computer
	8. System Software
	9. Programming

	10. What You See
	11. Hands On!
	12. On Your Own

	Search Glossary Appendix

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Last updated: 22 Jan 2008