Which tool is primarily used to gather data in the Measure phase?

The primary tool used to gather data in the Measure phase is the data collection plan. This tool serves as a blueprint for the data-gathering process, detailing what data will be collected, how it will be collected, and from where. It ensures that data collection is systematic and aligned with the goals of the Six Sigma project.

A well-structured data collection plan is critical because it helps define the metrics that are important for the project and outlines the methods to be used for gathering that data. This ensures consistency and reliability in the data collected, allowing the team to effectively analyze performance and identify areas for improvement.

In contrast, a control chart is used later in the process to monitor the stability of the process over time and to identify variations. Brainstorming sessions facilitate idea generation but do not specifically focus on data gathering. The fishbone diagram (also known as an Ishikawa or cause-and-effect diagram) is a tool used primarily for identifying and organizing potential causes of problems, rather than for direct data collection.