Distribution Analysis for variables

Distribution analysis for variable data is one of the critical analysis that help us understand how much
variation exists in the data. This in turn helps us understand how wide the process is and whether it falls within the specification limits.

There are several tools for studying distribution of variable data. The tools listed below are some of the popular ones:
1. Histogram
2. Stem and Leaf plot
3. Dot plot
4. Box plot

Histogram being the most popular to understand the nature of distribution of variable data. Dot and Stem & Leaf plot are more detailed versions for analyzing data distribution.
Box plots (also known as Box and Whisker plot) are used to compare distributions. Example for using a box plot would be to compare machine performance.

The figure below shows a comparison of the 4 tools.

We would love to hear which of the above tools have you used for analyzing distribution of variable data. Write to us at info@sybeq.com

Dangers of Analysis-Paralysis in Lean Six Sigma

Continuous improvement projects require teams to collect data and analyze it.
Lean Six Sigma method needs metrics and data to back up everything. Even the success of the LSS program is measured and tracked.

Sometimes Lean Six Sigma Green and Black belts analyze data more than needed. In LSS projects using the DMAIC approach the Measure phase is where hard data on the primary metric is collected. Preliminary data analysis begins in the Measure phase and continues into the Analyze phase where root causes are identified. Many LSS projects get stuck in the Measure or Analyze phase.

There are several reasons for this. Some of the key reasons are:
1. Data is hard to find/gather
2. There is too much or too little data
3. Incorrect data is collected
4. Green and Black belts over analyze the data
5. Preliminary data analysis does not reveal much so more data is collected

The Measure and Analyze phases of the DMAIC approach are most challenging. These phases take time and effort from the LSS team. The team needs to have the patience and persistance to get through these phases. The team leader (Green or Black belt) needs to get through the data collection and analysis portion efficiently/effectively. Without getting bogged down by data and not getting caught
in analysis-paralysis is the critical aspect to keep the project moving forward.

In our next blog post we will discuss the tools and techniques to overcome Analysis-Paralysis.

Have you experienced Analysis-Paralysis in an improvement project? How have you overcome it?