Run Charts

Run charts are used to show variations in the process over time or to show trends (such as improvements or lack of improvements) in the process. Differences in results will occur in processes because there is no such thing as a perfect process. When processes are considered in control, differences in results might occur because of common causes of variances or special-cause variances.

Common causes of variances come about as a result of circumstances or situations that are relatively common to the process you're using and are easily controlled at the operational level. Special-cause variances are variances that are not common to the process. For example, perhaps you have very detailed processes with specific procedures that must be followed in order to produce the output and a process gets missed. Or maybe your project requires the manufacturing of a certain part and a machine on the line has a problem and requires a special calibration. This is an easy set of terms to remember because their names logically imply their definitions.

For the exam, you should understand the three types of variances that make up common causes of variances:

Random variances Random variations might be normal, depending on the processes you're using to produce the product or service of the project, but they occur as the name implies, at random.

Known or predictable variances Known or predictable variances are variances that you know exist in the process because of particular characteristics of the product, service, or result you are processing. These are generally unique to a particular application.

Variances that are always present in the process The process itself will have inherent variability that is perhaps caused by human mistakes, machine variations or malfunctions, the environment, and so on, which are known as variances always present in the process. These variances generally exist across all applications of the process.

Common cause variances that do not fall within the acceptable range are difficult to correct and usually require a reorganization of the process. This has the potential for significant impact, and decisions to change the process always require management approval.

Exam spotlight

Project Management Made Easy

Project Management Made Easy

What you need to know about… Project Management Made Easy! Project management consists of more than just a large building project and can encompass small projects as well. No matter what the size of your project, you need to have some sort of project management. How you manage your project has everything to do with its outcome.

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