Perspectives on Standard Work

In the TPS Principles and Practice group on LinkedIn, I started a discussion by asking “What do we mean by ‘Standard Work’?” At that point, I saw it as whatever you do to ensure that same work is done the same way every time, regardless of time of day, production line, or factory; 96 comments later, my perspective has changed somewhat.

Ensuring consistency is, of course, essential but the tool to do it is Job Instruction (JI) rather than Standard Work. An operator’s complete job often involves multiple tasks, each of which has its own instructions. Standard Work builds on these instructions by specifying how these tasks are sequenced and combined to make effective use of people and equipment.

The main contributors were Len CanootSid JoynsonPeter WintonCasey NgDavid Hayden, MBAAchyut VaidyaEmmanuel JALLASEdward M. WhartonStephen DuquetteErik HagerJoachim KnufPaul Perry,  Cid LiSalvador D. Sanchez, Richard KunstAnders PenkerAndrew Williamson, and Steve Milner. The discussion also cited publications by Mike Rother, Art Smalley, John Shook, and Taiichi Ohno. If you want to see the whole discussion, please check it out on LinkedIn. This post is a synthesis , organized by topic and with illustrations added.

Why ask about Standard Work?

The House of Lean is a common metaphor. I use it sparingly, to make the point that the reason most Lean implementations in the US fail is that they are missing one of the two pillars:

House of Lean in Working with Machines

For this purpose, I don’t need to break down the details of what is in the Foundation or what the Goals are. Others provide many more details about the House of Lean, using it as a map of the whole system, with a prominent place given to something called “Standard Work” or “Standardized Work”:

As we can see, there is with variation in Standard Work  is supposed to mean. The Toyota description of Standard Work, for example, includes no reference to 5S or Visual Management, and explicitly excludes Job Instruction. The house on the right is from the Lean Enterprise Institute’s Lean Lexicon, and lists “Standard Work” and “Separating human work and machine work” as distinct entries but it is exactly what you accomplish with work combination charts, that are part of what Toyota calls Standard Work.

When you look it up on the Toyota Georgetown website or the LEI’s Lean Lexicon, it is about setting, for each operation, a takt time, work sequence, and required WIP, as expressed through a process capacity sheet, a work combination chart, and a work chart that is a layout diagram showing flows of parts and movements of operators between stations. (Click to see in full size.)

This is much more specific than what is meant by Standard Work is most discussions I have seen. I use capacity sheets, work combination charts and work station layout charts wherever you have to choreograph people working with machines, but I would not recommend them, for example, in manual assembly.

I have posted before about the work combination chart, as a powerful design tool for operator jobs, that also serves to communicate the sequence of tasks to operators, particularly new ones who are rotated into these positions. I see them as excellent tools, but it would not occur to me to label them “Standard Work,” because I don’t see any connection with the usual meaning of “standard.” I understand that “Standard Work” is an accurate translation of 標準作業 (Hyojun Sagyo), but I still don’t see a connection.

The following video clip, posted by JMA in Japan in 2009, shows what can be accomplished with work combination charts:

 

Standard Work and Process Stability

A process is stable if it can produce consistent output at a consistent pace. If it’s not stable, the first order of business is to stabilize it, but I don’t see standard work as the way to do it. You need to re-engineer the process to the point that its capability is no longer an issue and it is repeatable. Documentation and work instructions are an outcome of this effort, as needed to reduce the improved process to daily practice, but it is not the effort itself.

And the resulting documentation is not Standard Work. Standard Work, in the Toyota lexicon, is about takt time, work sequence, and required WIP, it doesn’t include process capability or even work instructions at the individual station level. It is only about the way you combine them in a line or a cell.

Is Standard Work the Best Known Way?

Most the Lean literature depicts Standard Work as an improvement backstop, a formalization of the improved process for the purpose of preventing backsliding. The following video is a quaint example of a PowerPoint animation used by a consultant to make that point. Note the yellow block preventing the wheel rolling back down:

Standard Work as “the best known way of doing the task” is the improvement backstop view, which I held without questioning it until I saw two articles disagreeing with it, and with each other, by Art Smalley .and Mike Rother. Mike Rother sees standard work as a target to shoot for rather than a backstop. Following is his rolling-wheel diagram:

Mike Rother's standard as a target condition

Mike Rother’s standard as a target condition

Yet another version was included in John Hunter’s review of Gemba Walkabout, and it shows standard work used to block progress instead of helping.

pdsa_blocked

These rolling-uphill diagrams remind me of the myth of Sisyphus, as described by Albert Camus. Sisyphus was a man condemned by the Gods to roll a boulder uphill everyday only to see it roll back down and start over, for eternity. See the following rendition by Marcell Jankovics:

Even if Sisyphus had had a backstop, it does not strike me as a particularly attractive metaphor for Kaizen.

Art Smalley sees Standard Work as a point of reference against which to measure future improvement. Taiichi Ohno does not say much about it in “Toyota Production System,”  but in Workplace Management,  he writes:

“There is something called ‘Standard Work,’ but standards should be changing constantly. lnstead, if you think of the standard as the best you can do, it’s all over. The standard is only a baseline for doing further kaizen. lt is kai-aku if things get worse than now, and it is kaizen if things get better than now. Standards are set arbitrarily by humans, so how can they not change?

When creating Standard Work, it will be difficult to establish a standard if you are trying to achieve “the best way.” This is a big mistake. Document exactly what you are doing now. lf you make it better than now, it is kaizen. lf not, and you establish the best possible way, the motivation for kaizen will be gone.

That is why one way of motivating people to do kaizen is to create a poor standard. But don’t make it too bad. Without some standard, you can’t say “We made it better” because there is nothing to compare it to, so you must create a standard for comparison. Take that standard, and if the work is not easy to perform, give many suggestions and do kaizen.”

John Shook on Standard Work

John Shook published three e-Letters on the subject of Standard Work in October 2009, called “Five missing pieces in your standardized work.”

In Part 1, he describes the goal of having the same work done the same way everywhere as distinct from Standard Work. He calls it “commonization” as a translation of 横伝(Yokoten). Literally, Yokoten means “lateral transfer,” but it is meant about know-how, not people. You invented a better way to do a job, and you propagate it to everybody else who does the same job.

When he discusses the distinction between Standard Work and Work Standards, Shook includes under Work Standards not just the time a task is supposed to take but all its technical parameters, such as critical dimensions, tolerances, etc.

He describes Kaizen and Standard Work as two sides of the same coin. You can’t have Kaizen unless you have Standard Work as the basis for improvement, and a Kaizen project is not finished until its outcome is incorporated in Standard Work. But Standard Work as he describes it —  with work combination charts — is used almost nowhere in American plants that claim to practice Kaizen. This means that some of the following must be true:

  1. The definition of Standard Work is too narrow. The need to specify takt times, work sequence and standard WIP is general, but different tools can be used to do it in different types of plants. A work combination chart, for example, is of limited value in a manual assembly process.
  2. Most plants that claim to practice Kaizen really don’t. In Japan, Kaizen designates small improvements to work methods, conceived and executed by the people who do the work, and US-style “Kaizen Events” are not Kaizen at all. A plant may run 50 Kaizen events per year and still not practice Kaizen. The means of implementing Kaizen include suggestion systems, that exist in many plants with varying success, and small-group, circle activities, that, in the US, are only found in Japanese transplants. As “Quality circles,” in the US, they were a fad in the 1980s; as Jon Miller pointed out in Quality Digest in 2011, circles are still going strong in Japan and in the rest of Asia.
  3. Some Kaizen activity is possible without Standard Work. What you really cannot do without is some metrics of before-and-after performance for the area that is improved, and these may be measured without Standard Work being in place.

The bulk of Part 2 is an example from Shook’s own experience on the Toyota assembly line in Takaoka in 1984. In Part 3, he describes Standard Work through the Purpose, Process and People framework, which he calls 3P. I had heard the “3P” acronym used before, by Shingijutsu people as the “Production Preparation Process,” which is something completely different.

Standard Work versus Work Standards

John Shook gives the following as examples of Work Standards:

  • Assembly – apply xx pounds of torque
  • Processing – heat treat at xxx degrees for x hours
  • Healthcare – provide xx medication at xx dose
  • Coffee – xx seconds for an espresso shot
  • Journalism – a weekly column of xxx words
Frederick Taylor quote

Frederick Taylor quote

Last month, the Institute of Industrial Engineers (IIE) had a conference in Chicago on “Managing Work Standards.” It was exclusively about how long it takes to do work, not about what the work is. It is a sensitive topic because it is associated in the minds of production operators with Taylor’s “scientific management” and his determination to prevent operators from colluding to curtail output, which he called “soldiering.” For all his great contributions, respect for humanity was not Taylor’s strong suit. He probably would have said that this man should have borrowed money from his parents to start a business…

What we are doing when analyzing video recordings of operations is more in line with what Frank and Lillian Gilbreth did: observing processes in order to improve them. The difference in thinking is obvious from just viewing the films the Gilbreths made about bricklaying operations.

The Gilbreths were working to make the bricklayers’ job easier, not to make them exert more effort, but Taylor’s name is better known, and his legacy is a challenge to live down.

I think we need to improve the terminology. Having two different concepts called “Standard Work” and “Work Standards” is confusing, especially when Toyota uses “Work Standards” to mean something other than the IIE. Incidentally, it is confusing in Japanese too.

How about using “Work Instructions” for what Shook calls “Work Standards”?

What is the Scope of Standard Work?

What is the scope of Standard Work? I have seen described, I don’t remember where, as the process as seen through the eyes of a first-line manager — also currently known as production supervisor, group leader, or area coordinator, and formerly as foreman. This is a member of management, with direct responsibility for quality, cost, and delivery by a few teams of operators.

This person sees the work as a sequence of tasks to which operators are assigned and among which they rotate as needed. The technical and human unit processes at each station are the foundation on top of which the supervisor works. This would be why Standard Work is focused on takt time, work sequence and work combinations, as opposed to tolerances and job instruction (JI).

Standard Work, Yokoten, and Revision Management

Also, Standard Work comes in the form of documents that are seen on the shop floor and that people are expected to follow. This makes them official, with revision numbers and approval stamps by stakeholders. Revision management on Standard Work is a whole other topic that I have not seen discussed anywhere.

Is Standard Work a Proper Focus for a Project?

Standard Work is a 2nd tier tool, like Visual Management, meaning that it is part of every project but never the focus of a project in its own right. In a brownfield situation, making “Standard Work” a project would lead you to attempt the precise documentation of work methods that need to be changed anyway, which would not be terribly useful and could bog you down for so long that you never get to do anything else.

On the other hand, if you identify specific dysfunctions in a process and organize a project to fix them, then you want the new and better way to be documented in such a way that it can be propagated across shifts and to other shops that do the same work.

Is Every Problem a Deviation from a Standard?

Peter Winton feels strongly that it is. And this is about standards in general, not just Standard Work. If every problem is a deviation from standards, however, we have an easy way of solving all our problems: let us just scrap the standards… But it would not solve all our problems, would it?

It would solve some problems, because there are futile standards. As David Meier pointed out, when you set a standard, you create an opportunity for deviation, and the need to respond to these deviations. So don’t standardize what you don’t need to.

The absence of a standard can be a problem. I remember a 2-in binder of specs on how to inspect an aerospace part that did not actually contain objective criteria for rejecting a part.

More generally, Standard Work, Job Instructions, Acceptance Specs, etc. are documents that are necessary to ensure a consistent output but not sufficient to guarantee that products will work for customers.

Products that are perfect on our terms may still displease customers, because they are using them in ways we didn’t anticipate. That is a problem, but it is neither the lack of a standard nor a deviation from any standard.

From what you write, I assume that you consider a standard to be an explicit statement of what should be, whether it is expressed as “this bolt should be tightened to x foot-pounds of torque,” or “this bolt should be tightened until the nutrunner’s light goes green.”

There are problems that cannot be expressed as a deviation from standard. As we all know, the proof of a cake is in the eating, which means that it cannot be tested before leaving the pastry shop. You serve this untested cake to your guests and it’s awful. The taste of the cake, in Juran’s terms, is a true characteristic. It is really what you are after but, more often than not, it is something you don’t know how to measure, and you can’t set a standard for.

You can measure some substitute characteristics of the cake, like its diameter, sugar content, or fat content. For these substitute characteristics, you can have specs to deviate from, and, if a cake is out of spec, you know it’s bad. It is, however, possible for a cake to meet all the specs you have defined and still taste awful. Whatever standards you define work as a one-way filter. What they allow you to reject is defective, but you don’t know that what they let through is not.

Philip Crosby

Philip Crosby

Joseph M. Juran

Joseph M. Juran

This was the old debate between Philip Crosby, for whom quality was “compliance to requirements,” and Juran, for whom it was “the agreement of reality with expectancy.” These are different philosophies, leading to different practices. For engineering students, for example, the Crosby approach would equate scoring As on exams with being a good engineer; in the Juran approach, there is more to it.

Is it “Standard Work” or “Standardized Work”?

It is “Standardized Work” that is the questionable translation. The Japanese term is 標準作業 (Hyojun Sagyo). 標準 (Hyojun) means Standard and 作業 (Sagyo) means work. Google translates 標準作業 to Standard Work and Standard Work to 標準作業. If you translate “Standardized Work” into Japanese, you get 標準化された作業 (Hyojunka sareta sagyo) and more syllables on both sides. I prefer the shorter version.

The same concept is called “Standard Work” by Ohno, “Standard Operations” in the JMA’s ‘Kanban, Just-in-Time at Toyota” and in Monden’s “Toyota Production System,” and “Standardized Work” in the LEI Lean Lexicon and on the Toyota Georgetown website.

If the terms were intended to designate different things, they should be more distinctive. I actually don’t think either one makes much sense because they are too generic and not descriptive. If you hear “page scanner” for the first time, you guess accurately what it does; for “Standard Work” or “Standardized Work,” good luck! Everybody thinks they know what it means, but all interpret it differently, which does not help communication.

Standard Work for Leaders and Managers

David Hayden brought up the subject of Standard Work for leaders, managers, and engineers. I see all jobs as routinely involving a mix of the following:

  • Repetitive tasks
  • Planned responses to events
  • Decision making in the face of unplanned events.

For production operators, it is mostly repetitive taks; for CEOs, mostly decision making. Standard Work, if defined as the combination of takt time, work sequence and standard inventory, is only applicable to production operators. In a broader sense, it can be applied to all repetitive activities.

A team leader in a cell, for example, does production work for about 50% of the takt time, and, in addition, is responsible for

  1. Maintaining the pace.
  2. Relieving other team members as needed.
  3. Supplying materials and tools to other team members.
  4. Keeping records.
  5. Coordinating changeovers.
  6. Coordinating 5S at the end of the shift.

Planned responses are not Standard Work in the strict sense. As far as I know, within Toyota in the US, they are organized under “Change Point Management” (CPM). In Japanese, as Casey Ng pointed out, it is called 変化点管理 (Henkatenkanri). About the scope of CPM, he wrote:

“For change point management such as a change in takt time , the introduction of new members to a  line, preparation to shut down, startup after week-end, resuming production after a power failure, introducing a new product, changing of new version of parts etc. There are all sort of standards which may generally call Standard Work.”

Standard Work and Project Management

Len Canoot asked whether the elements of Standard Work were translatable to project management.

The time it takes to do the work is the process time or the cycle time, not the takt time. In a line that works at a steady pace, the takt time is the interval between consecutive unit completions in order to meet the schedule within the work time available.

Does it translate to projects? It depends what kind of projects. If all your projects are “Kaizen events,” each one takes 11 weeks: 6 weeks of preparation, 1 week of focused activity, and 5 weeks of follow-up. It is a standard process, and you can to run them at fixed intervals in different areas of your plant. Most projects, however, are not reducible to this kind of cookie-cutter approach.

In a more general setting, there are tools you can use to manage a flow of projects, like capping the number in progress, so that participants’ attention is not spread too thin. At the very least, all your projects are either waiting to start, in progress, or finished. Often, however, they all go through a more detailed, common sequence of phases through which you can track them, even though the work required for a project through a given phase may vary.

Does that add up to standard work for projects?

Standard Work versus Standards in general

About the usual meaning of standard, this is what Wikipedia says about technical standards:

“A technical standard is an established norm or requirement in regard to technical systems. It is usually a formal document that establishes uniform engineering or technical criteria, methods, processes and practices.”

That covers the metric system and the internet protocols. Wikipedia also says the following about Standard Operating Procedures (SOP):

“In clinical research, the International Conference on Harmonisation (ICH) defines SOPs as ‘detailed, written instructions to achieve uniformity of the performance of a specific function’.”

When I see “detailed, written instructions,” it makes me think of the victorian-novel sized instruction binders that sit on shelves in many plants, unread, dusty, and full of obsolete information. Standard is also used in many other ways.

Standard Work and Changes in Takt Time

Anders Penker brought up the issue of the effect of changes in pace on Standard Work. One key reason you set up U-shaped cells, with the operator work area inside, is staffing flexibility. If it takes, say, 5 operators to operate at capacity, you can operate with 3, 2 or 1 operator at reduced rates, as seen below:

Takt time change in cells

Of course, your work chart and work combination chart for 6 operators are not applicable when you only have 4 or 3. But operating at a reduce pace with fewer people is something you can anticipate and plan for. You should have Standard Work ready for these circumstances, and post it as needed.

And there are circumstances where these charts are not applicable, for example when you apply the bucket-brigade method to make custom-configured products. But that is a different topic.

Mitigating “Mura,” or unevenness

The Japanese word Mura (ムラor斑) is the third member of the Muri, Muda, Mura axis of manufacturing evils. It means unevenness. In terms of volume of activity, if Muri refers to overburdening resources, Mura then really is the conjunction of overburdening some resources while others wait, or of alternating over time between overburdening and underutilizing the same resources.

Unevenness, however, is not only about volumes, but about quality as well. Unevenness in products is even synonymous with bad quality. From production managers facing “unpredictable” environments to academics promoting genetic algorithms or other cures, everyone bemoans how variable, or uneven, manufacturing is. The litany of causes is endless. Following are a few points that I think may clarify the issues:

  1. Mura in space, Mura in time, and Mura in space and time
  2. Degrees of severity: Deterministic, random, and uncertain environments
  3. What is special about Manufacturing?
  4. Internal versus external causes of unevenness
  5. Most useful skills in dealing with Mura

Mura in space, Mura in time, and Mura in space and time

Mura in space is imbalance in the work loads or utilization among resources at the same time; Mura in time, variability in the work load of a resource over time. The two can be present in the same factory. You may notice a kitting team working feverishly while the next one is waiting but, two hours later, you find the roles reversed.
Mura is often symbolized by two trucks arriving in sequence with different loads. I tend to think of working with Mura as moving around a city built on hills. A city built on a plain is even and easy to cross, and is often planned with a grid of numbered streets, like Manhattan in New York, or Kyoto. A city built on hills is uneven and offers many obstacles. San Francisco is built on hills, but its planners have chosen to ignore the terrain and slap on it a grid of straight streets. It makes for great views and dramatic car chases, but its steep slopes challenge your engine, your suspension, and your parking skills. Most hilly cities, like Nagasaki, Japan, for example, instead have streets that follow contour lines and therefore meander. The path by car from point A to point B may be longer than a straight line, but it is a smooth ride.

Navigating the peaks and valleys of product demand is like driving in a hilly city. If you just go straight, you keep alternating between pressing the accelerator and the brake, but by hugging contour lines, you can reach to your destination while going at a steady pace. This is what fighting Mura is about.

Degrees of severity: Deterministic, random, and uncertain environments

Some businesses are deterministic. They are “boring” and predictable. They have no variability. A manager once explained to me the electricity meter business in the market his plant was serving, as follows: “There are 20 million households with electricity meters in the country. Each meter lasts 20 years. Every year, I have to make 1 million.” The same products are made for many years, in stable quantities, and with mature processes that have no problem meeting tolerances. Of course, it only lasts until the advent of a disruptive technology, like smart meters.

This kind of environment is not common but it does exist. If your are in one, you should focus your improvement efforts on the opportunities it offers, and avoid tools that are overkill for it. For example, large, diversified companies that make a corporate decision to deploy the same planning and scheduling system in all their plants burden their simplest and most stable business units with unnecessary complexity.

Other business have variations that can be best be described as fluctuations around a smooth trend. If you make consumer goods, the demand every day is the result of decisions from a large number independent agents and will vary in both aggregate volume and mix, but within ranges that can be predicted. In terms of quality characteristics, if you fire ceramics, they shrink, by factors that still vary, even though we have been using this process for thousands of years. This level of variability is very common. The best term to describe it is randomness, and there is a rich body of knowledge on ways to work with it, including the Kanban system to regulate fluctuating flows and techniques to adjust processes in order to obtain consistent results from materials that are not. In ceramics, for example, you make your parts from a slurry that is a moving average of batches of powders received from the supplier, in order to even out their characteristics.

Contrast this with a toy manufacturer who cannot tell ahead of time which one or two products will be hits at Christmas, when most of the year’s sales occur. In process technology, there are similar differences in variability between mature, stable industries and high technology suffering from events like “yield crashes” during which a manufacturing organization “loses the recipe” for a product. Various terms are used to describe such situations, which, following Matheron, I call uncertainty. In such circumstances, the best you can expect from the techniques used to deal with randomness is to let you know that they no longer work. For example, dealerships can shield your plants from fluctuations in consumer purchases, where direct selling would let you find out sooner when demand drops for good or when consumer tastes change.

Calling our environment deterministic, random, or uncertain is always a judgment call. The deterministic electricity meter business turns uncertain with the advent of smart meters. If you view your environment as random, you expect fluctuations with a predictable range, and the signal of a shift into uncertainty manifests itself in changes beyond this range. You can use a variety of tests to detect that such as shift has occurred. Furthermore, with the possible exception of quantum physics, randomness is always in the eye of the beholder, and not intrinsic to a phenomenon.

What is special about Manufacturing?

Manufacturing is not the only kind of business to have high overhead; others include aviation or hospitals. In all such cases, companies must invest upfront in resources that pay off over time, and this is easiest to achieve with activities that place a balanced load on all resources and don’t vary over time — that is, without Mura.

Internal versus external causes of unevenness

Some unevenness comes from outside the organization, in many forms:

  • Fickle customers.
  • Seasonal variations in demand as in the toy industry.
  • Seasonal variations in supply, such as crop seasons in the food industry.
  • Changes in the macro-economy, such as a financial crisis.
  • Natural disasters, like earthquakes, tsunamis, and floods.
  • Raw materials with uneven characteristics, like ores or electronic waste for recycling.
  • Epidemics, as when 10% of your work force has the flu.
  • Unreliable suppliers.

You do not have the power to eliminate this kind of unevenness, but you can use countermeasures to mitigate its effects. On the other hand, you can and should eliminate unevenness that is self-inflicted. If you have not paid attention to balancing the work load of the various stations on your production lines, you are likely to have both overburdened and underutilized operators. Because of the different roles machines play, the workload can rarely be balanced across machines in a line, but the workloads of operators can be.

If you order materials from suppliers, for example by relying on an ERP system to issue orders by an algorithm for timing and quantities that you don’t undertand, you may well cause alternations of feast and famine in your suppliers’ order books for materials that you, in fact, consume at a steady pace. This creates unevenness not only in your suppliers’ operations, but also in your internal logistics. In The Lean Turnaround, Art Byrne explains that, at Wiremold, he eliminated volume discounts and incentives for Sales to book the largest possible orders. Instead, he preferred a steady flow of small orders, that smoothed the aggregate demand.

Not all resources need to be treated the same way. You want resources that can be described as producers to be generating useful output all the time. Other resources, which we may call responders, must be available when needed, and this is a radically different objective. Unevenness is an enemy for producers, but, unless responders’ work loads provide enough slack, they are unable to respond. Firefighters fighting fires 100% of the time would be unavailable when a new fire breaks out, and the same logic applies to maintenance technicians and operators who work as floaters on a production line. And it applies to machines as well as people. In a machine shop, for example, machines that carry out the primary processes, like hobbing a gear or milling pockets in a slab, are producers, while devices used for secondary processes, like deburring or cleaning, are responders. This is often, but not always, related to the cost of the machines, with expensive machines as producers and cheap ones as responders. However, some of the most expensive equipment, like machining centers, may be bought for its flexibility more than for its capacity, in which case its primary role is to respond to orders for short runs or prototypes.

Most useful skills in dealing with Mura

Permanently uneven workloads among operators can be addressed by balancing, using Yamazumi charts for manual operations and work-combination charts for operations involving people and machines. If the unevenness pattern shifts or oscillates over time, then the workload itself needs to be smoothed, with is done by the various techniques known as heijunka.

Many organizations are not aware of Mura as a problem, and, when aware, are oblivious to patterns in the unevenness that can be used to mitigate or eliminate it. Management, for example, may be struggling to cope with occasional large orders and fail to notice that they arrive like clockwork every other Wednesday from the same customer. A modicum of data mining skills is needed to recognize such patterns in the records of plant activity.