Learn how to calculate, interpret, monitor, review, adjust, and maintain process capability ratio (PCR) over time and enhance your business process performance.

ð¤You will often find process capability ratios used more often in areas such as manufacturing and healthcare where the margin for error needs to be more tightly controlled than in the service industry - i.e. telephone call interactions. Matt Rebeiro - Challenge the Status Quo #bpi #process #lss #LeanSixSigma #PCR

Last updated on Sep 21, 2024

How do you monitor and review process capability ratio over time and make adjustments as needed?

Process capability ratio (PCR) is a measure of how well a process can meet the specifications or requirements of a product or service. It compares the natural variation of the process output to the allowable variation set by the customer or the industry. A higher PCR means a more capable process that produces less defects and waste. But how do you monitor and review PCR over time and make adjustments as needed? Here are some steps you can follow to improve your business process performance using PCR.

1 Calculate PCR

The first step is to calculate the PCR for your process. You need to collect data on the process output and measure its mean and standard deviation. Then you need to know the upper specification limit (USL) and the lower specification limit (LSL) for the output, which are the maximum and minimum values that the customer or the industry accepts. The PCR is calculated by dividing the difference between USL and LSL by six times the standard deviation. For example, if USL is 10, LSL is 6, and the standard deviation is 0.5, then the PCR is (10-6)/(6*0.5) = 1.33.

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Matt Rebeiro

Strategic Advisor | Startup | Tech | Ops | Product | GTM Consultant | Marketing | SaaS | AI Process Automation Strategy | Founder of the Tech Retriever | Toronto | New York | Vancouver | San Francisco |
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ðŸ¤”You will often find process capability ratios used more often in areas such as manufacturing and healthcare where the margin for error needs to be more tightly controlled than in the service industry - i.e. telephone call interactions. Matt Rebeiro - Challenge the Status Quo #bpi #process #lss #LeanSixSigma #PCR

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Imrul Kayes

Co-Founder, Camel Tech | Business Automation Expert
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To monitor process capability ratio (PCR), you first need to calculate it by comparing the spread of your process to the allowed limits. This gives you a clear view of how well your process is performing. In my roofing business, we tracked PCR by measuring how much our actual work output varied from our ideal targets. Calculating PCR helped us see if we were consistently meeting customer needs or if adjustments were required. Keeping an eye on this number made it easier to spot areas for improvement and ensure quality stayed high.

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2 Interpret PCR

The second step is to interpret the PCR and compare it to the target value or benchmark. A common target value for PCR is 1.33, which means that the process output is within the specification limits 99.73% of the time, assuming a normal distribution. A PCR of 1 or higher indicates that the process is capable of meeting the specifications, while a PCR of less than 1 indicates that the process is not capable and needs improvement. You can also compare your PCR to the industry average or best practices to see how your process performs relative to others.

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Imrul Kayes

Co-Founder, Camel Tech | Business Automation Expert
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Once you calculate the process capability ratio (PCR), itâ€™s important to interpret what it means. A PCR greater than 1 means your process is capable of meeting requirements. If itâ€™s less than 1, you may need to make improvements to meet targets. I remember reviewing the PCR for our material usage in my roofing business. When we saw the ratio was below 1, it signaled that we were using too much material. This led us to investigate the problem and make necessary adjustments. Interpreting PCR helps you understand where your process stands and where to focus your efforts.

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3 Monitor PCR

The third step is to monitor the PCR over time using control charts or other statistical tools. Control charts are graphs that plot the process output data over time and show the mean, the upper control limit (UCL), and the lower control limit (LCL). The UCL and LCL are calculated based on the standard deviation and represent the normal variation of the process. If the process output stays within the control limits, it means that the process is stable and in control. If the process output goes beyond the control limits or shows a pattern or trend, it means that there is a special cause of variation that needs to be investigated and corrected.

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4 Review PCR

The fourth step is to review the PCR periodically and analyze the causes of variation and the opportunities for improvement. You can use tools such as Pareto charts, fishbone diagrams, or root cause analysis to identify the factors that affect the process output and its variation. You can also use tools such as histograms, box plots, or scatter plots to visualize the distribution and relationship of the process output and its specifications. You should review the PCR at least once a month or whenever there is a significant change in the process or the customer requirements.

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5 Adjust PCR

The fifth step is to adjust the PCR by implementing improvement actions based on the analysis and review. You can use tools such as brainstorming, benchmarking, or quality function deployment to generate ideas for improving the process capability. You can also use tools such as plan-do-check-act (PDCA) cycle, Six Sigma, or lean to execute, monitor, and evaluate the improvement actions. You should aim to increase the PCR by reducing the process variation, increasing the process mean, or widening the specification limits, depending on the situation and the customer needs.

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Imrul Kayes

Co-Founder, Camel Tech | Business Automation Expert
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Adjusting the process capability ratio (PCR) involves making changes to your process to improve performance. This can include reducing variation, tightening control limits, or improving efficiency. In my experience, we had a project where our PCR was too low due to inconsistent material usage. We adjusted the process by standardizing how materials were measured and stored. Over time, this reduced waste and improved the PCR. By consistently monitoring and adjusting your process, you can ensure it meets the desired capability level.

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6 Maintain PCR

The sixth step is to maintain the PCR by standardizing and documenting the improved process and ensuring its compliance and consistency. You can use tools such as standard operating procedures (SOPs), checklists, or audits to document and communicate the process requirements and expectations. You can also use tools such as training, feedback, or recognition to motivate and empower the process operators and stakeholders. You should continue to monitor and review the PCR regularly and make adjustments as needed to sustain and enhance the process capability and performance.

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7 Hereâ€™s what else to consider

This is a space to share examples, stories, or insights that donâ€™t fit into any of the previous sections. What else would you like to add?

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Sumin Valiyaveetil

VP, Global Markets (MSM Unify) | Market Entry Specialist | Strategic Partnerships (B2G, B2B, B2C) | Process Improvement | Business Process Reengineering
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Example Scenario: Initial Assessment: A pharmaceutical company assesses the capability of its packaging process with a target Cp of 1.33. Regular Monitoring: Monthly data collection and Cp calculation reveal fluctuations around Cp = 1.25, indicating slight process variability. Review and Analysis: Root cause analysis identifies inconsistent sealing temperatures as a primary cause. Adjustments: Temperature control systems are calibrated and operator training is enhanced. Monitoring Continues: Subsequent Cp calculations show improvement to Cp = 1.30, closer to target. Continuous Improvement: The company implements ongoing monitoring and periodic reviews to sustain and further enhance process capability.

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Directory

How do you monitor and review process capability ratio over time and make adjustments as needed?

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1 Calculate PCR

2 Interpret PCR

3 Monitor PCR

4 Review PCR

5 Adjust PCR

6 Maintain PCR

7 Hereâ€™s what else to consider

Business Process Improvement

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