Root Cause Analysis Basics....
In the previous steps of the quality improvement process the concern was gaining an understanding of the process and documenting it. In this step the quality improvement team begins the Plan-Do-Check-Act Cycle by identifying the root cause of any lack of process capability.
The data looked at so far by following the previous steps of the quality improvement process measure the output of the process.
To improve the process, you must find what causes the product or service to be unsatisfactory. For this you should use a fishbone diagram (cause-and-effect diagram) to identify potential problems.
Once a team identifies all of the possible causes, it should collect data to determine how much these causes actually affect the results . People are often surprised to find that the data do not substantiate their predictions, or their gut feelings, as to causes.
The team can use a Pareto chart to show the relative importance of the causes they have identified.
5 Why Analysis is another tool that is widely used to discover the root cause of poor process capability.
More often than not, people fix a problem by dealing with issues that are immediately apparent. While it may provide a quick fix, the problem tends to rear its ugly head in the same form, or with a different face later on. Fixing the problem permanently is what you should aim to do.
Here's an example:
Suppose you had a garden which was wilting and dying. You could make it look better in the short term by cutting and weeding, but surviving plants and flowers will continue to wilt and would still be dying.
Instead, you need to investigate the cause of the wilting.
Once you know what the true issue is you can fix it.
5 Why Analysis
The concept of 5-why is simple:
Find solutions and countermeasures to fix the problem.
Step 1: Select the process to be improved and establish a well-defined process improvement objective. The objective can be established by the team or come from management.
Step 2: Organize a team to improve the process. This involves selecting the “right” people to serve on the team; identifying the resources available for the improvement effort, such as people, time, money, and materials; setting reporting requirements; and determining the team’s level of authority. These elements should be formalized in a written charter.
Step 3: Define the current process using a flow chart. This will generate a step-by-step map of the activities, actions, and decisions which occur between the starting and stopping points of the process.
Step 4: Simplify the process by removing redundant or unnecessary activities. It's likely that people may be seeing the process on paper in its entirety for the first time from Step 3. This can be a real "eye-opener" which will prepare them to take the first steps in improving the process.
Step 5: Develop a plan for collecting data and collect baseline data if it's not already being collected. This baseline data will be used as a "yardstick" later in the quality improvement process. This begins the
evaluation of the process against the process improvement objective established in Step 1. The flowchart in Step 3 is used to help determine who should collect data and where in the process data should be collected.
Step 6: Assess whether the process is stable. Create a control chart or run chart out of the data collected in Step 5 to gain a better understanding of what is happening in the process. Future actions of the team are dictated by whether special cause variation is found in the process.
Step 7: Assess whether the process is capable. Create a histogram to
compare the data collected in Step 5 against the process improvement objective established in Step 1. Usually the process simplification actions in Step 4 are not enough to make the process capable of meeting the objective and the team will have to continue on to Step 8 in search of root causes. Even if the data indicate that the process is meeting the objective, the team should consider whether it is feasible to improve the process further before going on to Step 14.
Step 8: Identify the root causes which prevent the process from meeting the objective. Use a cause-and-effect diagram or brainstorming to generate possible reasons why the process fails to meet the desired objective.
Step 9: Develop a plan for implementing a process change based on the possible reasons for the process’s inability to meet the objective set for it. These root causes were identified in Step 8. The planned quality improvement involves revising the steps in the simplified flowchart created after changes were made in Step 4.
Step 10: Modify the data collection plan developed in Step 5, if necessary.
Step 12: Assess whether the changed process is stable . Same as Step 6, use a control chart or run chart to determine process stability. If the process is stable, the team can move on to Step 13; if not, you should return the process to its former state and plan another change.
Step 13: Assess whether the change improved the process. Using the data collected in Step 11 and a histogram, the team determines whether the process is closer to meeting the process improvement objective established in Step 1. If the objective is met, the team can progress to Step 14; if not, the team must decide whether to keep or discard the change.
Step 14: Determine whether additional process improvements are feasible. The team is faced with this decision following process simplification in Step 7 and again after initiating an improvement in Steps 8 through 13. In Step 14, the team has the choice of embarking on continuous process improvement by reentering the model at Step 9, or simply monitoring the performance of the process until
further improvement is feasible.
May 10, 16 09:24 PM
A Quality Control Plan is a documented description of the activities needed to control a process or product. The objective of a QCP is to minimize variation.
May 10, 16 08:49 PM
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May 10, 16 07:28 PM
The Weibull distribution is applicable to make population predictions around a wide variety of patterns of variation.