Systems implementation approaches: which method runs the old system and the new system simultaneously for a defined period to compare results and reduce risk?

Introduction / Context:
Choosing how to switch from a legacy solution to a new one affects risk, cost, and user confidence. Among classic cutover strategies—direct, pilot, phased, and parallel—only one keeps both systems live concurrently to validate outputs during the transition.

Given Data / Assumptions:

• The organization wants to mitigate go-live risk.
• There is budget and capacity to run two systems in tandem.
• Stakeholders will compare outputs to verify equivalence.

Concept / Approach:
Parallel implementation operates legacy and new systems at the same time, processing the same transactions for a limited period. Discrepancies surface quickly, enabling fixes before full cutover. This approach increases operating cost temporarily but reduces the probability of catastrophic failure.

Step-by-Step Solution:
Review definitions of direct, pilot, phased, and parallel.Identify the method that explicitly runs both systems in production together.Select “parallel” as the correct approach.

Verification / Alternative check:
Implementation playbooks often include “parallel run acceptance criteria” such as reconciling reports and transaction counts for N cycles—evidence of this method’s risk-control nature.

Why Other Options Are Wrong:
Direct: immediate switchover; no overlap. Pilot: limited scope or location first. Phased: functions migrate in stages but typically disable legacy portions as they move. “None” is incorrect because a precise method exists: parallel.

Common Pitfalls:
Underestimating duplicate work and data synchronization issues; failing to define reconciliation rules and exit criteria for ending the parallel period.

Final Answer:
parallel