Overview

Process definition and data collection plans build validity and consistency into data. Data reflect process performance and provide insight and knowledge about a process. If a team wants to evaluate variation in a process, it will need to collect data. A data collection system is a type of measurement system.

Any business or organization must know "where it stands" currently if it is attempting to achieve a defined goal(s). Six Sigma uses a measurement system to establish a baseline, which will identify where a product/service is in relationship to defined goals. To establish a baseline, current measurements are needed. Once a business knows where it is and where it wants to go, existing gaps can be determined and the business can also assess the efforts and resources needed to reduce the gap(s) in product/service quality and thereby achieve the goal(s).

Think about the SIPOC process ( Supplier- Input- Process- Output- Customer), in which measurement occurs at three different stages of the process inputs, process, and outputs.

Input measures represent measures of the key CTQs (critical to quality characteristics) placed on suppliers. Input measures indicate supplier performance and also correlate to output measures. Input measures are defined as independent variables and are represented by the letter X. Process measures are internal to the process and include key control elements for improving the output measures. Output measures are defined as dependent variables and are represented by the letter Y. Meaningful process measures...