Tool guide: Pareto or Pie Charts?

Introduction

Have you ever had the pleasure of running a Six Sigma project with an important champion, such as a C-Level? Of course, your champion wants to know what you are working on, and why – even when they do not have sufficient time to dig into the specific tools of DMAIC.

Getting the champion's buy-in and their final decision is vital to project success. But how can you convince an important decision maker without wasting their time on technical details?
In this paper, we discuss an easy and effective method of displaying project data with Pie Charts.

All functionality for creating and customizing Pie charts as described in this article are standard EXCEL or Open Office functions.

Every Six Sigma practitioner should be familiar with a Pareto Chart: we categorise our data into bins in order to figure the "essential few“ where we will concentrate our improvement efforts.

Pareto charts are a very powerful tool in the Six Sigma decision making process. Yet, they require background information and some understanding of what is going on behind the scenes.

The scenario:

Your Six Sigma project is running well. To report on the Analyze phase, you schedule a briefing with the Champion. As their schedule is packed, they can only offer you a five-minute spot. During that time, you must show them what you got, where you are heading and what you need from them.

Maybe those five minutes are the only time you can get for the remainder of the month.

Being a diligent belt, you load up all your data into a presentation. As you approach defect counts and root causes, you dig out your Pareto chart. The data is accurate, the chart complete.

You are satisfied because you have a clear Pareto effect and it seems obvious what should be done now.

Example:

Illustration 1: An example Pareto Chart

And then your champion asks: “Wait, not so fast. What do those bars and the line mean? Why is the red line in the middle of the graph?” As you start explaining the basics of a Pareto chart, the clock is relentlessly ticking away, and before you have gotten to the meeting's core - that is, the plain facts and the decisions you require for proceeding further - your champion receives an urgent call and you're out: “thank you, see you next time”.

Why Pie Charts?

Without diminishing the value of a Pareto chart for data analysis, they might simply be inappropriate to inform a champion and lead decision making.

A Pie chart is quickly understood and does not burden the watcher with unnecessary information:

Illustration 2: The same data in a Pie Chart

Your Champion will immediately understand that you see potential for taking care of at least half of the problems in one shot, and you can spend the rest of your meeting to get the support you need in order to make this happen.

Colours are your friend

The coloration of the Pie Chart can be used to guide the decision making process into the direction you want:
A pie chart like this, early on in the Six Sigma project: a quarter of the chart is shining red - a big portion of the problem is “out of scope”: Is the project really properly defined?

A light green slice suggests “This problem will easily go away”.

You can use any kind of hues for your Pie chart to “hide” additional information: complexity of the solution, Return on Investment, difficulty of the change process and so on.

Control Phase Report

You can resort back to your Pie Chart in the project closure report when the target process is under Control.
A translucent white area measures your project success in quality terms, and in our example, without further explanation, the observer sees that over a third of defects have disappeared.

Illustration 3: Pie Charts for Control Reports

Closing Words

The proper representation of data has a significant impact on the acceptance of your project. Pie Charts are an easy and effective way to make the data you gathered in your “lab” attractive and comprehensive to observers and project members.
Use a Pie Chart in the right place and get the decisions and support you need!