AS ICT Module 2

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AS ICT Module 2
11.2 - Verification and Validation

• Understand the distinction between accuracy of
  information and validity of data.
• Explain possible sources and types of error in
  data capture, transcription, transmission and
  processing. Describe methods of preventing and
  reducing such methods.
• Describe appropriate validation techniques for
  various types of data process, from data capture
  to report generation.

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11.2 - Verification and Validation
Accuracy of Data / Information
For a computer system to produce useful
information from the data it is given, it has to
be accurate.
DATA INPUT
ADDRESS 42 Acacia Avenue, Eastlands
Estate, Boston, Lincolnshire, NG12 4NL UK
POSTAL COST 28p
COMPUTER OUTPUT
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11.2 - Verification and Validation
Accuracy of Data / Information
If the data is not accurate, the information it
produces from the data is not accurate. This is
known as GIGO GARBAGE IN GARBAGE OUT
DATA INPUT
ADDRESS 42 Acacia Avenue, Eastlands
Estate, Boston, Lincolnshire, NG12 4NL USA
POSTAL COST 1.50
COMPUTER OUTPUT
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11.2 - Verification and Validation
Accuracy of Data / Information
To help prevent errors, verification and
validation methods are employed. However, these
DO NOT prevent mistakes, they attempt to reduce
the amount made by an operator.
DATA INPUT
ADDRESS 42 Acacia Avenue, Eastlands
Estate, Boston, Lincolnshire, NG12 4NL USA
The country you have specified in the address
does not conform to the address convention
used. Please check your data input.
COMPUTER OUTPUT
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11.2 - Verification and Validation
Accuracy of Data / Information
Accuracy means correctness. Verification and
validation attempt to ensure accuracy, but can
only do this within a RANGE defined by the
programmers of a software / solution.
In this example, the database into which this is
being entered will have been told to accept only
a two-letter entry in this field. Inaccurately
typing in the USA (as a three-letter word)
causes the database validation to question the
operator.
ADDRESS 42 Acacia Avenue, Eastlands
Estate, Boston, Lincolnshire, NG12 4NL USA
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11.2 - Verification and Validation
Accuracy of Data / Information
BEWARE some data can be valid, but inaccurate!
DATA INPUT
ADDRESS 42 Acacia Avenue, Eastlands
Estate, London, Lincolnshire, NG12 4NL UK
POSTAL COST 28p
COMPUTER OUTPUT
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11.2 - Verification and Validation
Where can errors occur?
TRANSCRIPTION
PROCESSING
TRANSMISSION
DATA ENTRY
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11.2 - Verification and Validation
How can errors be prevented?
VERIFICATION
VALIDATION
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11.2 - Verification and Validation
Differences Between Verification and Validation
Verification
establishment of the correctness of a theory or
fact.
A verification check ensures that data is
correctly transferred into a computer from the
medium that it was originally stored on.
DUAL INPUT (incl BATCH
PROCESSING
ON SCREEN PROMPTS
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11.2 - Verification and Validation
Differences Between Verification and Validation
Validation
To confirm or corroborate. To declare valid.
A validation check is an automatic check made by
a computer to ensure that any data entered into
the computer is sensible.
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11.2 - Verification and Validation
Differences Between Verification and Validation
Validation
Presence Check
Type Check
Parity Check
VALIDATION CHECKS
Format Check
Check Digit
Range Check
Length Check