Data quality controls: in transaction processing, a key verifier machine is primarily used to control which stage?

Introduction / Context:
Accurate data entry is critical to downstream accounting, inventory, and customer systems. One classic control is key verification (also called double-key entry), often implemented using a key verifier machine or software function. Understanding where this control sits in the transaction flow prevents errors from propagating to later stages.

Given Data / Assumptions:

• Key verification compares two independent entries of the same transaction data.
• The aim is to detect keystroke errors before posting or transmission.
• “Transaction entry” refers to the data capture stage at terminals or workstations.

Concept / Approach:
Key verification is designed for the input phase. Two operators (or one operator twice) enter the same fields; the system flags discrepancies for correction. This reduces transcription errors, increasing accuracy before records move to communication channels or batch/real-time processing engines.

Step-by-Step Solution:

Verification / Alternative check:
Auditing and internal control manuals situate key verification among input controls (range checks, format edits, check digits) executed at entry time.

Why Other Options Are Wrong:

• Data communication: occurs after entry; verification should happen earlier.
• Computer processing: also occurs post-entry; errors should be filtered before processing.
• Transaction origination: refers to business event creation (e.g., a sale); verification is a data capture control, not a business event control.

Common Pitfalls:
Relying on downstream edits only; the lowest-cost fix is at the point of entry.

Final Answer:
transaction entry