What is the most appropriate test effort estimation technique for testing an upgrade of an ERP system that has a previous version in production?

The most appropriate test effort estimation technique in the context of testing an upgrade of an ERP system that has a previous version in production is metric-based estimation. This method leverages historical data and metrics from the previous version of the system to estimate the effort required for testing the upgrade.

By using metrics from prior testing efforts, teams can establish benchmarks and identify patterns in the testing process, which can provide accurate predictions for the time and resources needed for the current upgrade. This technique is particularly beneficial for ERP systems where changes may be incremental. Historical metrics can inform the team about the types of issues discovered previously, areas that may require more testing, and the overall complexity of changes.

In contrast, other techniques may not leverage the existing knowledge effectively. For instance, effort-based estimation relies heavily on subjective judgment rather than historical data, which can lead to discrepancies if team members’ experiences differ. Expert-based estimation might rely on the insights of a few individuals, which can also introduce bias if those experts do not have a comprehensive understanding of all aspects of the previous system's testing outcomes. Schedule-based estimation focuses more on timelines rather than the complexity or the real effort involved, which can be misleading in a dynamic environment where upgrades can have varied impacts.

In summary, metric-based estimation