The Six Sigma DMAIC (Define, Measure, Analyze, Improve, Control) methodology can be defined as a roadmap for problem-solving and process improvement. The define phase states the problem, the measure phase collects data and uses it to measure performance. The third phase i.e the analyze phase focuses on the identification and statistical analysis of root cause which in turn directly leads to performing a root cause analysis. It is about analyzing the data collected in the measured phase.
The key steps performed in the analyze phase are:
• Defining performance objectives
• Identifying value/non-value added process steps
• Identifying sources of variation
• Determining the root cause(s)
In order to do this effectively, different types of analysis are used. Below is the list of various types of analysis performed in the analyze phase of the DMAIC methodology:
1. Process Map Analysis: The Analyze phase begins with a good look at the detailed process map. It is a planning and management tool that describes the flow of work visually. The main purpose of process map analysis is to improve efficiency. It provides insight into a process, help teams brainstorm various ideas for process improvement, increase communication among the team and provide process documentation. Process mapping is used to identify bottlenecks, repetition, and delays. It also helps to define the process boundaries, process ownership, and process responsibilities.
The benefits of process map analysis:
• Increase the understanding of a process
• Analyze how a process can be improved
• Improve communication among the individuals engaged in the same process
• Provide process documentation
• Plan projects effectively.
The tools for process map analysis:
• Plan-Do-Check-Act cycle(PDCA cycle)
• FMEA(Failure Mode and Effect Analysis)
• Fishbone diagram
2. Graphical Analysis: The next step involves using the tools and techniques that are linked to the Analyze phase. Most of these tools end up with a graphical result. The next step in the process is to understand the graphs from the bottlenecks specified by the process map analysis. This is done because directly conducting a statistical analysis can be expensive as it involves extensive data collection.
The benefits of graphical analysis:
• It allows to quickly learn about the nature of the process
• It enables clarity of communication
• It facilitates looking at individual data points
• Monitoring and tracking data over time becomes easier.
Graphical analysis helps in making summaries of characteristics of data in an effective and efficient manner.
The tools for graphical analysis:
• Line charts
• Time series plots
• Pie charts
3. Statistical Analysis: Statistics are described as a field that involves tabulating, representing, and defining data sets. Statistical methods are defined as the use of collected data and quality standards to find innovative ways to enhance products and services. They are a formalized body of techniques involving attempts to infer the properties of a large collection of data.
The benefits of statistical analysis:
• Employ predictive analytics to anticipate future trends.
• Monitors, controls and improves processes
• They prove the validity of the process.
• Statistical analysis help guide future actions
The tools for statistical analysis:
• Hypothesis testing
• Regression analysis
• Statistical process control
The Analyze Phase is often not given enough importance and, without analysis, teams tend to jump to solutions before knowing the actual root causes of the problems. This is the most important phase of all five phases of DMAIC. The ideal analysis is for the teams to brainstorm the potential root causes and develop hypotheses as to why the problems exist and then work to prove or disprove their hypotheses.
Analysis can take various forms. Some Six Sigma projects tend to use a lot of diagrams and worksheets, while others prefer discussion and list making. The proper method is the one that works best for your team, given that the end result is successful.