The Key Concepts of Control Charts

control charts - Invensis Learning

Also known as the Shewhart chart, control charts are used for statistical monitoring of operations in an organization. The details plotted are in order of time. A regulation map still includes the typical center axis, the higher axis for the upper control limit, and the lower control limit line. Those lines are based on historical evidence. 

By matching existing data with those figures, you will conclude whether the process variance is stable (in control) or erratic (out-of-control, caused by unusual causes of change). This versatile method for gathering and reviewing data can be used by several industries and is one of seven simple information tools.

Characteristics of Control Charts

If a certain quality characteristic has been measured or estimated from an example, the quality value per sample number or time is shown in the control chart. The diagram usually contains a middle line which describes the mean benefit for the process under management. The map also displays two additional horizontal lines, named the upper limit of control (UCL) and the lower limit of control (LCL). These control parameters are described in such a way that virtually all data points fall within those limitations as long as the system remains in service.

control chart - Invensis Learning

What Is a Process?

Control charts are the foundation of statistical process control (SPC), after all. What we do is simply a procedure. It may be to fill out a cost sheet, check a person in a hospital, drive to work, fill a prescription, etc. All of those processes yield a production-either a commodity, or a service. But, on top of that, the methods produce results. SPC is essentially taken from the data produced by the process and used to monitor and enhance the process. Collecting data on an approach is also useful in four dimensions: consistency, quantity, timeliness, and cost.

When To Use a Control Chart?

Control charts are used in the following scenarios: 

  • If ongoing processes are managed by identifying and fixing issues when they arise 
  • Predicting the range of results expected from a procedure 
  • If a mechanism is stable (in Statistical Control)
  • When evaluating process variance patterns from specific causes (non-routine events) or typical causes (a built-in tool) 
  • When deciding whether your quality management initiative can focus on preventing particular issues or making profound process improvements

Control Charts Should be Used Everywhere

Monitor maps are one of the systematic techniques which may be used to support processes quality control. They are of use in multiple types of procedures. Just not in the process at all. You can’t really make a general statement that a control panel would only remain in operation here and never work there. However, almost always, there’s a chance to chart data over time to see what’s going on.

The first question you need to address is: Why use a monitor chart? You should have a target. You may be operating on a Six Sigma project and would like to clarify the type of diversity and consumer needs.

Over time, you would like a component reduced. For a particular purpose, maybe you want to map a process. First, the trick is to establish a goal.

Basic Procedure

  • Choose the required Data Management Chart. 
  • Set the required timeline for data collection and plotting. 
  • Download data, compile a map, and analyze the data.
  • Look upon the monitoring panel for “out-of-control signs.” 
  • Mark it on the map when one is found, and investigate the source. 
  • Record how you have researched, what you have found, the cause, and how it has been rectified. 

Types of Control Charts 

There are various types of control charts that are used for different purposes. Let’s just take a look at them.

C Chart

C chart is a type of control chart that displays the number of non – conformities that appear in a given category, objects that are out of spec. Data is obtained in different types, all of the same size. In this sort of control map, each point represents a set of items instead of each point representing a single product, and its position on the y-axis shows you how many nonconformities there are in that category. This form of control diagram has an average line as well as an upper limit. Any data subjects over the upper control limit indicate that there were so many mistakes on a sample.

R Chart

An R chart is a monitor map that tells you the distribution of no more than ten objects in a category. It’s similar to a c map when it shows you different types of items over time, but the r chart shows you the set rather than non-conformities. The variation here applies to how far away the dimensions of the products differ. A brick used to build homes, for example, may have a right width of 0.1 inches for a brick that is advertised to be 6 inches. 

This means that the brick will range in length from 5.95 inches to 6.05 inches everywhere because of variations in the output. This illustration tells you the selection of 10 or fewer objects in a small category. Any value less than 0.1 is appropriate for the tiles, but something above is unacceptable. This form of control chart would have a regular centerline, a lower bottom control limit (usually y = 0), and upper management limit the highest permissible variance for a good product.


Control charts are a comparatively straightforward tool for receiving, controlling, and improving processes when quantitative structures are at play. They allow you insight into the operation’s efficiency and help managers concentrate exclusively on the deviation that needs remedial intervention or what means a system is ready for improvement.

Suppose you’re looking for the best way to implement using Control Charts in your organization for better outcomes, then you should consider taking up some of the popular quality management certification courses with Invensis Learning today. 

Some of the popular quality management certification courses that individuals and enterprise teams can take up are:

Lean Six Sigma Green Belt Certification Training

Lean Six Sigma Black Belt Certification Training

Lean Six Sigma Yellow Belt Certification Training

Lean Fundamentals Training

RCA through Six Sigma Training

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Diego Rodriguez works as a Six Sigma Black Belt professional for a leading manufacturing company. He possesses ample experience in various aspects of quality management, such as Lean, Six Sigma, Root Cause Analysis, Design Thinking, and more. His primary focus is to conduct tests and monitor the production phase and also responsible for sorting out the items that fail to meet the quality standards. Diego’s extensive work in the field has resulted in being an honorary member of quality associations globally. His areas of research include knowledge management, quality control, process design, strategic planning, and organizational performance improvement.


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