The objectives of control are:
To ensure that all data are processed
To preserve the integrity of maintained data
To detect, correct and re-process all errors
To prevent and detect fraud
Types of Controls
The different controls can be grouped under five headings:
Data protection controls
Types of Error
System designers must guard against the following types of error:
Missing source documents
Source documents on which entries are omitted, illegible or dubious
Data preparation errors
Machine Hardware faults
Even in advanced systems checking of source documents is necessary. Checks may include:
Scrutiny to detect:
Illogical or unlikely entries
Reference of the document to stored data to verify entries
Re-calculating to check calculations made on the document
Data Collection Controls
The collection of data for processing involves transcribing it into a form suitable for machine processing.
There is a real possibility of error at this stage.
Controls must be imposed to prevent or detect errors at this stage.
The type of control depends on the method of data collection used:
Data Collection Controls 2
On-line systems. These depend on the data displayed on a VDU or printed being checked by the operator before being processed.
Character recognition. With these techniques, accuracy depends on the character reader detecting any doubtful character or mark.
Validation Checks 1
A computer can't notice errors in data being processed in the same way that a human operator can.
Validation checks are an attempt to build into computer programs the ability to detect and report incorrect data items
Checks can be made at two stages:
Input - when data is entered
Updating - after processing
Validation Checks 2
The main types of validation check used are:
Presence. Data are...