A cause and effect diagram is a tool that shows the relationship between a quality characteristic (effect) and possible sources of variation (causes). As shown below, the effect could be a problem that needs to be solved or the goal of the process. The effect would then be listed on the cause and effect diagram. The causes involve everything that might trigger the problem. Cause and effect diagrams are also called fishbone diagrams (because of their shape) and Ishikawa diagrams (because of their developer).

The cause and effect diagram is one of...

A scatter diagram shows the relationship between two variables. For example, you might want to compare the speed you drive with the time it takes you to get to work, or to compare the heights and weights of children, or to compare the steam usage in a plant to the outside temperature. This is what scatter diagrams do.

Suppose you are a warehouse manager. Overtime is a concern to you since it is something your boss watches closely. There is overtime every day. You have a theory that the overtime is simply caused by the work level – the number of lines that are picked each day in the...

Our previous blog introduced histograms. Histograms tell you four things about your process. Remember what those were? If not, see our previous blog, What is a Histogram? . Histograms also can give you insights to things you might not normally see. The example below demonstrates this.

Here is the background information for you. A supplier sends in weekly shipments of one raw material to you. There is one raw material characteristic that is key to how it performs in your process. The supplier provides you with a Certificate of Analysis with...

A Pareto chart helps you answer questions. What is the reason for the most rework or scrap in your organization? Which customers complain the most? What keeps us from getting the books closed after the end of the month. These questions are common in organizations, but we don’t always agree on the answer. This is where the Pareto chart comes in. A Pareto chart is a data-based approach to determining what “vital few” issues you should be working on.

The Pareto chart is named after Vilfredo Pareto, an Italian economist, who discovered that 80% of Italy’s wealth was held by 20% of the...