Chapter 7 Flashcards
(95 cards)
Nature of Computers
- fast
- do not think the way humans do
- do not get tired but succumbs to technical problems
- follows the dictum: “do it right the first time, do it right all the time.”
Three broad classes of application controls
- Input Controls
- Processing Controls
- Output Controls
Designed to ensure that the transactions that bring data into the system are valid, accurate, and complete
Input controls
Data input procedures can be:
- Source document triggered (batch)
- Direct input (real-time)
Classes of input controls:
- Source document controls
- Data coding controls
- Batch controls
- Validation controls
- Input error correction
- Generalized data input systems
Five CAATTs approaches used for testing application logic:
- Test data method
- Base care system evaluation
- Tracing
- Integrated test facility
- Parallel simulation
Source document input requires human involvement and is prone to clerical errors.
True
Direct input employs real-time editing techniques to identify and correct errors immediately.
True
Controls in systems that are using physical source documents.
Source document controls
Control procedures over source documents:
- Use pre-numbered source documents
- Use source documents in sequence
- Periodically audit source documents
Checks on the integrity of data codes used in processing.
Data Coding Controls
Three types of processing errors:
- Transcription errors
- Single transposition errors
- Multiple transposition errors
Three classes of transcription errors:
- Addition errors
- Truncation errors
- Substitution errors
Occurs when an extra digit or character is added to the code.
Addition errors
Occurs when a digit or character is removed from the end of a code.
Truncation errors
The replacement of one digit in a code with another.
Substitution errors
Occurs when two adjacent digits are reversed.
Single transposition errors
Occurs when non-adjacent digits are transposed.
Multiple transposition errors
Data coding controls:
Check digits
A control digit added to the code when it is originally assigned that allows the integrity of the code to be established during subsequent processing. (suffix, prefix, embedded)
Check digits
Check-digit techniques:
- Sum of digits
- Modulus 11
The steps in modulus 11:
- Assign weights
- Sum the products
- Divide by the modulus
- Subtract the remainder from the modulus to obtain the check digit.
- Add the check digit to the original code to yield the new code.
An effective method of managing high volumes of transaction data through a system, especially paper-fed information system.
Batch controls
Batch controls provide assurance that:
- All records in the batch are processed.
- No records are processed more than once.
- An audit trail of transactions is created from input through processing to the output stage of the system.