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Control Chart Functions
Basically, typical control charts measure variations, defects, and unstable process. Through control chart fluctuation analysis, project managers can determine areas that need to be addressed, changed, are acceptable or need improvement.
Process variations in control charts are analyzed before process improvement can begin. In most control charts, there are common causes for variation in data or special causes. Common causes quickly identify an element that is outside of the control realm, a cause of Mother Nature if you will.
Special causes, once identified, consist of items that need to be revisited or changed in order for the project to continue. Many project management methodologies now implement control chart forms including Six Sigma and Agile management.
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What Can Be Identified Can Be Controlled
Consider the use of a control chart to analyze a process or procedure. Through control chart analysis, a project manager will be able to analyze the reasons for variations over time and decide which variations affect project outcomes.
Control charts are often used in the analysis world of healthcare. How many patients are seen with contagious or infectious diseases per region would be an example. Control chart forms are also used in medical and drug trials to identify variations in sample pools. By identifying fluctuations, causes can be determined and improved upon or reported.
In a software development project, a control chart may show how many times the software exceeds acceptable error or goes beyond what is acceptable. All control charts forms have a mean or base range and both upper and lower control limits to determine variations. In some projects, without control charts, unacceptable fluctuations may go unidentified.
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Examples and Downloads
Here at Bright Hub PM, there are many examples of how control charts work as well as free templates to guide you. Heidi Wiesenfelder offers great explanations on control charts in her article, Types of Control Charts.
Control chart forms define both attributes and variations (attribute type charts and variable type charts). Ms. Wiesenfelder discussed attribute type control charts in her article Types of Attribute Control Charts. Attribute control charts include p, c, and u charts. In another of Heidi’s articles, you'll find examples of variable control charts or X-Bar/Range Control Charts.
Click on the links below for some free control chart form templates you can download without ado, including:
Beyond utilizing these control chart forms in your projects, keep in mind that effective control charts allow for both upper and lower control limits and if a median range is utilized correctly, elements falling within these ranges can be controlled.
Control charts can also determine practical or assigned deviations and are helpful especially in Total Quality Management or TQM. The resultant data determined and obtained through control chart forms can assist the project manager is creating good quality assurance and risk management plans.