March 1, 2020

By Darren Dolcemascolo

In last month's article, we talked about the first part of a problem solving process: defining the problem.  This month, we are going to talk about gap analysis.  This is the process by which we identify the critical causes or root causes to a problem.  A gap analysis involves investigation.  The problem solving team must deeply understand the process, collect relevant data, and then analyze the data in order to determine what are the critical causes. 

The first step in gap analysis is to observe the process in detail.  Documenting the current state process utilizing a process map is a good way to get started with this process.  The team may even do this as part of the problem definition process described in the last article.  What's next?  After the team has observed and documented the process, a fishbone or cause and effect diagram might be the best next step.  The fishbone diagram is drawn to resemble the skeleton of a fish, with the issue (problem or process condition) on the right side. The major cause categories are written in the boxes on the left side of Cause and Effect Diagram. Summarize the major causes under the categories. The basic categories are usually people, methods, machines, and materials. Sometimes, other categories such as measurements and/or environment are added. The step by step process is:

• Set up the fishbone diagram with the categories on a whiteboard or flip chart paper on a wall.
• Write down the problem on the right hand side- at the head of the fish.
• Hand out post-it notes to each team member.
• Have each team member write down the fcauses/factors observed about the process that fall under the categories listed.
• Discuss each cause or factor, and work with the team to prioritize these for further investigation.

After the fishbone is complete, we want to verify/validate the causes we have identified.  This can be done through further observation, experimentation and/or data collection.  We want to investigate the causes to identify which are the most important causes.   The best tool to display this is the pareto chart, which can be created after collecting data.  A pareto chart can be created using Microsoft Excel, and the basic procedure for creating one is as follows:

• Based on the fishbone, identify categories with the team. 
• Create an electronic or paper form for data to be collected.  usually this can be accomplished with a check sheet.
• Have some Collect relevant data by category.  For example, in the pareto chart below, a check sheet with causes for not meeting the planned production for the day was created, and the operators checked off each occurrence in which one of the failures occurred by category.
• After the data are collected, Microsoft Excel can be used to create the pareto chart.  In the newest versions of Excel, this is a standard chart.

 

Once we understand and have verified what the root cause or top contributing causes are to our problem, we are ready to begin identifying countermeasures.  We will talk about this in a future article.

 

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