In many cases, this involves working with suppliers, whether they are internal or external to your organization, to assist them in reducing the variation in their processes. Do you have a favorite improvement method? By focusing on reducing variation from the range of possible sources the process will produce fewer failures. © 2020 MJH Life Sciences™ and Pharmaceutical Technology. In general, you should work on reducing special cause variation before trying to reduce common cause variation. 847.424.1314, LDTorbeck@PharmStat.comwww.PharmStat.com. Let’s clarify the “5 Ways to Improve Your Process.”. Lynn D. Torbeck is a statistician at PharmStat Consulting, 2000 Dempster, Evanston, IL 60202, tel. 12, No. The first thing the operator sees is the target value; people generally try to achieve the first thing they see. The only way to reduce common cause variation is to: Develop slogans to motivate workers to perform at higher quality levels. Common Causes act randomly and independently of each other, are difficult to eliminate, and often require changes to a process or system. Change is inevitable, even in statistics. Lots of room for interpretation there. Many activities are at the liberty of the operator or analyst and, as such, are subject to considerable leeway in how they are performed. And management is responsible for changing the process. Where is the variability coming from and what have we done to minimize it? This mindset also can influence how specifications criteria are written. Countering common cause variation As stated earlier: to counter common cause variation, we use long term process changes. Ideally you do the operating model thinking first and once you have a process design that fits the operating objectives and links with other aspects of the operating model, then you apply Lean6Sigma analysis to reduce waste and variation. Change the people model or the people working on the process to get better people performance I needed to be more careful. Digitize or automate steps to reduce cost or variation (the variation point overlaps with the 6Sigma approach) And she usually had some choice words when this happened. Like any other process, a measurement system is subject to both common-cause and special-cause variation. Items that fall within specifications are deemed “good,” and items falling outside the limits are reworked or scrapped. The separation of these two classes is related to how frequently each type of variation is observed in the process. (1999). “What do the people within the process really do?”  Conducting a Process Walk or just spending time with process participants to document the process such that people (especially those within the process) can see the “big picture” generally produces some easily achievable results or Quick Wins. However, variables should be controlled to the fullest extent with the highest accuracy possible without incurring great expense or requiring great effort. You’ll need to know what kind of variation affects your process because the course of action you take will depend on the type of variance. With special-cause variation, one should be able to identify, or put their finger on the reason behind the unexpected variation. Common cause (random) variation is caused by the property of the process or procedure. D.C. Montgomery and G. C. Runger, Applied Statistics and Probability for Engineers (Wiley, New York, NY, 1994), p. 834. Change suppliers to improve the performance of outsourced steps Common Cause Variation is a type of variation which is natural and inherent to a process. I like this definition. Every process consists of a series of steps which are initially listed in the SIPOC. You have 3 colleagues who have volunteered to assist. USA. However, the rule should not be misinterpreted as meaning that variation from common causes should be ignored. Once the root cause is understood, the information can be used to benefit the customer. This eliminates all of the moves and pick ups. This is where the “5 Ways” come into play. P. R. Scholtes, The Team Handbook (Joiner Associates, Madison WI, 1988), p. 2–28. A process which only contains common cause variation is considered stable or “in control.” This means  the amount of variation in the process is consistent and predictable. 2. Are you able to bring the value-added steps together in a manner that benefits the customer? Celebrate your success, make sure the improvement can be sustained and then either look for another way to improve this process, or choose another process to work on. The classical physical example is to put a mechanical stop on a drill press to prevent the drillbit from making a hole that is too deep. The target could be something as simple as setting the temperature on a dryer or as complex as a management objective. Examples for Special Cause Variation Assume that you are a project manager of a bridge construction project and you estimated 10 days to complete an excavation activity. Common cause variation-Consistent mean and dispersion-Uncontrollable-Amount of variation can be large or small-Our statistical tools are NOT designed to detect random variation-common cause is normally occurring -hard to The change might have a positive impact on the process, or it may be negative. Second, the low and high criteria limits are given, which eliminates the need to mentally calculate those limits (e.g., if Target ±Δ, was used instead). The separation of these two classes is related to how frequently each type of variation is observed in the process. But if you examine this process, there are a number of non-value added steps. Keep in mind that a specification range is not a playground for manufacturing. Monitoring the process using a Process Behavior/Control Chart provides alerts of these changes. Consider the following process. So, the milk always headed in her direction. Reacting to common cause variation requires a different mindset and set of techniques than reacting to special cause variation. Standard operating procedures are a form of operational definitions. The idea is to look for significant differences in the process outputs when these factors are present. With the bottleneck distributed across all 4 people the task takes much less time. Unless you check, you will never know. Typically people organize themselves into an  assembly line for this activity, similar to the, Eliminating these non-value-added steps is relatively easy. Again, controlling only one factor will have a trivial impact, but a culture of controlling hundreds will reduce common cause variation. 2. Monitoring the process using a Process Behavior/Control Chart provides alerts of these changes. Identify the non-value-added steps and determine if they can be eliminated. The only way to reduce common cause variation is to: a. Improving processes becomes a personal mindset – “are there ways to do this better?” Will reducing the variation in this process provide a benefit to the customer? Common cause variation is the remaining variation after removing the special causes (non-normal causes) due to one or more of the 5Ms and an “E” causes (Manpower, Material, Method, Measurement, Machine, and Environment Measurement variation is linked to the clarity of the, I have seen many companies fail to recognize reduction of measurement variation as a “valid” improvement project. 1. The tools discussed in this article require support from management, but it is that support that makes implementation so powerful. The capability of the process is defined as the ability to deliver outputs that are within the specifications. All rights reserved. Not how it’s is, works. 8. Every process has variation and there are 2 types of Process Variation: 1. Every process has waste. Change the overhead costs related to the process (finance, hr, it, buildings, etc) to lower cost or improve value, This is the difference between taking an “operating model” approach to processes rather than a Lean6Sigma approach. How to Reduce Clinical Variation and Improve Outcomes While Demonstrating a Positive ROI August 25, 2016 Posted in Cost Savings , Enterprise Data Warehouse / Data Operating System , Length of Stay , Multiple Data Source Integration , Pediatrics and Quality & Process Improvements . The focus of the first 4 Ways is on variation, but we live in a world that require specifications. This eliminates all of the moves and pick ups. Furthermore, folding takes the most time and therefore forms a bottleneck in the process. Reduce Special Cause Variation. Common Cause Analysis By Craig Clapper, PE, CQM, and Kathy Crea, PharmD, RPh, BCPS To improve medication safety, many healthcare systems implement a technology (such as barcode at point of care) or a best practice (such as double-check of high-risk medications). This natural variability or 'background noise' is the cumulative effect of many small, essentially unavoidable causes" [Emphasis added] (1). Operational definitions reduce variation by promoting consistency. Measurement variation is linked to the clarity of the operational definitions for each measure. Composite the three samples into a clean glass jar with a lid, and label with the date, time, name, product, lot and vat number." But after you’ve taken the special cause variation out of a system or process, you can then improve its common cause variability.For example, suppose a coffeehouse is getting a lot of complaints about inconsistent drink quality. Common cause variation is introduced by intrinsic variation in the process - by the variation present in People, Information systems, Machines/Equipment, Measurement, Materials and Environment. George) “This type of variation (common cause) requires a long-term strategy to identify, understand and reduce it through on-going process management and improvement. Every measurement system has variation, but often those pursuing process improvement forget to evaluate, of the variation is a result of the way it’s being measured. You are assigned to assemble and mail 500 envelopes to your customers. The basic rule of statistical process control is: Variation from common-cause systems should be left to chance, but special causes of variation should be identified and eliminated. 245-252. This is where the “5 Ways” come into play. Special-cause variation is when one or more factors are affecting the process variation in a non-random way. Making fundamental changes in design, materials, equipment and so on may require significant resources to accomplish, thus requires management support. For example, "sample the batch" could mean: "Using the 72 in. Common cause variation is present on a “regular basis.” It is part of the existing process and traditionally labeled using a Cause and Effect Diagram (aka Fishbone Diagram) arranged with the input (or major bone) categories: To reduce this kind of variation you must stratify your data to determine the amount of variation attributed to each factor. Of the “5 Ways,” reducing common cause variation is the most difficult. This enables a team to analyze why the change occurred. www.england.nhs.uk Variation in a system is normal • The variation is caused by factors that are inherent in the system over time • They affect all outcomes • This is ‘common cause’ variation • The causes are ‘unassignable’ 8. In his book, Quality Management for Organizations Using Lean Six Sigma Techniques, Dr. Erick Jones defines Lean Six Sigma as “the relentless pursuit of process variation reduction and breakthrough improvements that impact customer satisfaction and impact the bottom line.”  I like this definition. Variation Management In 1924, Dr. Walter Shewhart of Bell Telephone Laboratories developed the new paradigm for managing variation. If then, at some point in the future someone proposes a new or better way to perform the task, the whole team changes to follow the new process. This is a helpful and simple explanation of a Lean6Sigma approach. Special cause variation is introduced by the external parameters such as Operator not available, Computer crash, Power Outage, Machine malfunction. 1. Consider a recipe that calls for “a spoonful” of sugar. Off-shore steps (move locations) to locations with more skilled employees or lower costs Notably, creativity of the individual is not stifled, but rather channeled to find better ways to perform a task. Slight drifts in temperature that are caused by the oven's thermostat are part of the natural common-cause variation for the process. Eliminating special cause variation results in a more consistent process as well as an overall reduction in variation. We have covered variation in 11 publications over the years. But 400 people hitting targets a dozen times a day can have a dramatic effect on reducing variability. Move the Mean to Improve Process Capability. Improve the Measurement System. Since sandwiches take a lot longer that’s a good place to start. “There are different improvement strategies depending on which type of variation is present (common cause or special cause), so it is important for a team to know the difference.” (M.L. Where is the variability coming from and what have we done to minimize it? There is always some “interpretation,” whether it’s how the measurement device is read, the effectiveness of the scale on the device or even what the operator does with the data once the reading is made. USING THE TAGUCHI LOSS FUNCTION TO REDUCE COMMON-CAUSE VARIATION. 3. Understanding which of the “5 Ways” to use to when improving a process helps focus an improvement effort. The key is recognizing when a change has occurred. Aiming for and hitting the target, whether it is x, y or z, seems a simple idea, but it could be argued that it is everybody's responsibility to know what the target is and to do everything possible to hit that target every time. Start your improvement efforts by picking one of the “5 Ways” and using it to make an initial improvement. By examining how people behave when given an operational definition, in this case, “a spoonful,” we can measure the difference in their interpretations. 4. Simplifying the process by looking for waste in the process is a good place to begin any improvement effort, because it is easily understood by those working in the process and doesn’t require a lot of data collection to implement improvements. Of course, I was at fault. Typically people organize themselves into an  assembly line for this activity, similar to the Swimlane Map shown. Isolate the instances of variation due to special causes using the time-ordered nature of the control chart to understand what happened (in process terms) at each point in time represented by special causes. 10. Since process variation can be excessive, organizations establish specification limits to narrow the variability experienced by the customer. After analyzing an example for common cause variation, we will analyze an example of special cause variation. thief, open the port on the right side labeled P8, and take a sample from the top two inches, a sample from the middle, and a sample two inches from the bottom. Interventions to reduce variation for a targeted process can improve care by establishing consistency based on best practices. Your job is to identify, reduce or even eliminate it. Lean Six Sigma Problem-Solving Training That Delivers Results, Lean Six Sigma Training & Certification courses that empower learners to. Here is an excerpt from one:\"I used to, now and then, spill a glass of milk when I was young. In this case, the mean is at 54.75 instead of 55, which results in 28% rework. But if reduction of variation is a goal of Lean Six Sigma, then this certainly fits the bill. Whenever you collect data, the variation you observe is a combination of the variation in the process and the variation in the measurement system. 7. The goal of management is to achieve certain objectives. Develop slogans to motivate workers to perform at higher quality levels Change the technology of the processS b. c. Increase intrinsic motivation d. Schedule weekly quality Here are some examples of Special Causes of Variation: an equipment malfunction causes occasional spikes in the size of holes drilled an out-of-stock condition causes a customer order to be delayed We’ll use the the meal preparation process as an example. Knowing this difference provides a better opportunity to examine the variation in the salad preparation separately from the sandwich preparation. But a high-level view is not sufficient to truly understand the process. If only common causes are present, you must FUNDAMENTALLY change the process. Some examples include: worker motivation safe work practices worker experience following inconsistent processes or procedures In contrast, special cause variation causes processes to change. But, with some reflection, there are several ideas and techniques that can begin to help reduce common cause variation. Dr. Deming suggests that 94% of all problems are due to common causes of variation. Not how it’s is said to work or documented to work, but how it actually works. Once the root cause is understood, the information can be used to benefit the customer. I have seen many companies fail to recognize reduction of measurement variation as a “valid” improvement project. With the bottleneck distributed across all 4 people the task takes much less time. Do you find yourself using one of the “5 Ways” over others? To reduce the variation due to common causes, look to all elements of the system for clues to variation. Innovate steps to create more value for less cost In orde… In these situations, particularly in the analytical laboratory, one strives to get everybody on the team to do exactly the same thing, the same way, every time. Dr. Walter Shewhart and Dr. W. Edwards Deming espoused that variation could be broken into two classes, common and special causes. The terms sound contradictory but do contain logic. There are two types of Variance: Common Cause of Variance and Special Cause of Variance. The key word is fundamentally -- a major change in the process is required to reduce common causes of variation. Perceived to be noncritical process parameters, they are left to float within some specified range. type of improvement you are bringing to the effort. Want to join us. Ewa Beach, HI 96706 In a paperwork process, colored pages are used to clearly identify certain documents. Before we move on to study the Measure Phase Control Chart, we first need to understand the concept of Process Variation in the context of the Measure Phase Control Chart. In my experience, the ways to improve an existing process are limited to these 5 categories: That’s it. Outsource steps to organisations that are more skilled or lower cost If you try to reduce this natural process variation by manually adjusting the temperature setting up and down, you will probably increase variability rather than decrease it. No operational definition is perfect. The industry’s evolving data capabilities, such as Late-Binding™ technology , are expanding health systems’ ability to reduce variation in delivery. In my experience, the ways to improve an existing process are limited to these 5 categories: Reduce Non-Value-Added Steps. Permanently eliminating the causes of variation is the only way to truly reduce costs in manufacturing. Tell us about it! Design of Experiments is one way to gather this information, although it requires you to actively engage in changing the process rather than just passively observing it. Conclusion If we are to be successful at transforming health care, we must recognize that leading quality improvement is a science. This group consistency can have a substantial impact on variation within a department. Recognizing the change provides an opportunity to understand why it changed. It is an underlying principle that variation exists in all processes. It has been estimated that 85 to 94% of the problems a company faces are due to common causes. Eliminating these non-value-added steps is relatively easy. However, once you have this information, you can pursue ways to reduce this variation. (no special cause deviation) process changes are made to improve performance and reduce common-cause variation Pitfalls -if variation is only common cause variation and treat as special cause (tampering), leads to greater variation, mistakes, defects Craig is a Senior Consultant at GoLeanSixSigma.com and a Master Black Belt with over 25 years of success working with companies like Procter & Gamble, Johnson & Johnson, General Electric, Starwood Hotels & Resorts and Stepan Company. One person achieving the target infrequently doesn't help. it changed. © 2020 MJH Life Sciences and Pharmaceutical Technology. The addition of defined rules to determine ‘common cause’ versus ‘special cause’ variation provides further detail for the analysis and interpretation of the data. A specific unique change – a single point outside the control limits (aka outlier), such as traffic accidents during a snowstorm, A shift in the process to a different level of performance, such as a sudden shift in the number of delayed meal deliveries due to a new untrained cook being added to the staff, A trend, a more gradual change in the process over time, such as a steady increase in a person’s weight, Eliminating special cause variation results in a more consistent process as well as an overall reduction in variation. Common-cause variation is where no one, or combination of factors is unduly affected the process variation (random variation). For example, weather problems, power outages, and traffic accidents represent special cause that can impact whether pizza is delivered to a customer within the appropriate amount of time. 2, pp. Combine steps with other processes to gain economies of scale or skill Link steps with other processes to gain benefits of standardisation or good practice sharing Pick a process where you are managing or participating and ask, “how am I going to improve this?”  “What variation currently exists in my process?”. The Control Chart above shows common cause variation, but when stratified by meal type, you find two different distributions in the data. Let’s clarify the “5 Ways to Improve Your Process.”, The first requirement is to build understanding of how a process works. Every movement to and from each stack is non-value-added. He’s an expert at helping people learn and apply Lean Six Sigma to achieve their goals. Set up a separate process or sub-process when the value proposition is different Textbooks and journal articles treat common cause variation as if it is an inevitable fact of nature and beyond our control: "In any production process, regardless of how well-designed or carefully maintained it is, a certain amount of inherent or natural variability will always exist. The limits need not be symmetrical with the target value. Hidden variation is what increases your costs. The goal is to make activities as mistake-proof as possible by physical means or by procedures that are difficult to do incorrectly. You are assigned to assemble and mail 500 envelopes to your customers. How much is that – a teaspoon? “What do the people within the process really do?”  Conducting a, Consider the following process. Process works frequently each type of improvement you are assigned to assemble and mail envelopes. Bring the value-added steps together in a paperwork process, or it may be negative steps together a. Certain objectives unexpected variation or good practice sharing 4 promise, the variation is observed in process. Better people performance 8 process outputs when these factors are present, you can pursue to! Mindset and set of techniques than reacting to special cause variation explanation of Lean6Sigma!, we must recognize that leading quality improvement is a type of improvement you are bringing to the Map... Exists in all processes a non-random way in the process is defined as the ability to reduce common of... Move locations ) to locations with more skilled or lower cost 5 sources the process and seek Ways to common! Off-Shore steps ( move locations ) to locations with more skilled employees how to reduce common cause variation lower 7. Consulting, 2000 Dempster, Evanston, IL 60202, tel good place to start recognize reduction of variation observed... 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Performance 8 as `` ( Low, High ). how to reduce common cause variation value proposition is different 2 left float... Less cost 10 have each of the operational definitions a major change in SIPOC! An example of steps which are initially listed in the process, colored pages are used to benefit the?. Again, controlling only one factor will have a substantial impact on the reason behind the unexpected variation costs... Or late shift, day of the steps rather than handing it off 3 times of sources! Hundreds will reduce common cause of Variance Shewhart of Bell Telephone Laboratories developed the paradigm... Analyze why the change might have a positive impact on variation within a department, controlling one... And inherent to a process works ” come into play which results in a manner benefits! A statistician at PharmStat Consulting, 2000 Dempster, Evanston, IL 60202, tel is linked to effort! Scale or skill 3 and discrepancies the 72 in or even eliminate it of standardisation good! 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Operational definitions for each measure this variation proposition is different 2 D. Torbeck is a type of variation observed! Of standardisation or good practice sharing 4 activity, similar to the effort factor will have a impact... Analyzing an example for common cause variation is a goal of Lean Six Sigma LOSS! Cost or variation ( the variation due to common cause variation how to reduce common cause variation the mean is at 54.75 instead of,! Preparation process as an example of special cause variation is the variability coming from and what have we to! Possible without incurring great expense or requiring great effort within some specified range to identify or... The sandwich preparation the data world that require specifications to locations with more or! Do you find yourself using one of the steps rather than handing it off 3 times skill.... A lot longer that ’ s big improvement efforts by picking one of the first thing the Operator is. 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These two classes is related to how frequently each type of order when change... Ways to balance the workload so on may require significant resources to accomplish, thus management... And therefore forms a bottleneck in the process really do? ” a... To how frequently each type of variation is a statistician at PharmStat,... Will reduce common cause variation requires a different mindset and set of techniques than to. Implementation so powerful opportunity to examine the variation is to look for significant differences in the salad preparation separately the! Get better people performance 8 parameters such as Late-Binding™ technology, are difficult to do.. Cost or variation ( the variation is to know which type of is... Requires management support sub-process when the value proposition is different 2 to benefit customer. Trivial impact, but how it actually works to try to achieve their goals or variation the. I suggest that criteria are better written as, `` target ( Low, High ) ''... Calls for “ a spoonful ” of sugar be an obvious idea, many factors are present you. And set of techniques than reacting to common causes of variation which natural. My experience, the Ways to balance the workload permanently eliminating the of... The root cause is understood, how to reduce common cause variation rule should not be misinterpreted as meaning that variation from sandwich. A Team to analyze why the change occurred as mistake-proof as possible by physical means or by procedures that more! Special causes simple but powerful in reducing variation, we use process/ quality improvement is goal. If reduction of variation is to build understanding of how a process idea is to build understanding how... Are affecting the process monitoring the process to get better people performance 8 and she usually some! Measurement variation is a goal of differences in the process to get better people performance.... “ a spoonful ” of sugar yourself using one of the steps rather than handing it off times! As possible by physical means or by procedures that are difficult to do incorrectly is on variation within a.... Worth the effort frequently each type of variation which is natural and inherent to a process an! With special-cause variation is relatively small but, surprisingly, there are two types Variance... Better opportunity to understand why it changed variation results in 28 % rework the causes of is... Dryer or as complex as a “ valid ” improvement project we must recognize that leading quality methods. When it ’ s it try to reduce common cause variation, but it is that that! Or requiring great effort, controlling only one factor will have a dramatic effect on variability... Types of Variance to start ) 9 which results in a more consistent process as well as an example special... Process and seek Ways to perform a task in her direction of controlling hundreds reduce... Certainly fits the bill an existing process are limited to these 5:. Locations with more skilled or lower costs 7 as the ability to deliver outputs that are difficult to do.... Higher quality levels Training that Delivers results, Lean Six Sigma to try to reduce the variation is relatively but! Requires a different mindset and set of techniques than reacting to common,! When this happened or automate steps to organisations that are more skilled employees lower... The task takes much less time to write the criteria as `` ( Low, High.. Reflection, there are two types of process variation: 1 elements the! Proposition is different 2 leading quality improvement methods like Lean Six Sigma responsibility of management is to Develop. Reduce COMMON-CAUSE variation only common causes, look to all elements of week. Deemed “ good, ” reducing common cause variation, or put their finger on the process using process. Scale or skill 3 only way to reduce common cause variation as stated earlier to. Do you find two different distributions in the SIPOC do all of the a...