Chapter 7 Flashcards
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.
Two documents used to accomplish batch control objectives:
- Batch transmittal sheet
- Batch control log
The batch transmittal sheet captures relevant information such as:
- A unique batch number
- A batch date
- A transaction code
- The number of records in the batch
- The total dollar value of a financial field (batch control total)
- The total of a unique non-financial field (hash total)
Refers to a simple control technique that uses non-financial data to keep track of the records in a batch.
Hash total
Are intended to detect errors in transaction data before the data are processed.
Validation controls
Three levels of input validation controls
- Field interrogation
- Record interrogation
- File interrogation
Types of files in a computer-based systems:
- Master file
- Transaction file
- Reference file
- Archive file
Audit trails in computer-based systems are less observable than in a traditional manual system.
True
Generally contains account data.
Master file
A temporary file of transaction records used to change or update data in a master file. Examples are sales orders, inventory receipts, and cash receipts.
Transaction file
Stores data that are used as standards for processing transactions.
Reference file
Contains records of past transactions that are retained for future reference.
Archive file
Examples of transaction files
- Sales orders
- Inventory receipts
- Cash receipts
Examples of reference file
- price list used for preparing customer invoices
- list of authorized suppliers
- employee rosters
- customer credit files for approving credit sales
Hierarchy of data
- Field (name, year level)
- Record (for every student)
- File (all bsa students)
- Database (all HNU students)