Glossary
Whether you’re new to the quality and continuous improvement arena or a seasoned expert seeking detailed information on a specific quality topic, you should find what you need in our Glossary of Terms.
Explore the concepts, tools, applications and technical terms that make up the world of continuous improvement.
Natural Tolerance
The Natural Tolerance limits of a process are normally these limits between which the process is capable of producing parts. Natural tolerance limits are expressed as the process mean plus or minus z process standard deviation units. Unless otherwise stated, z is considered to be three standard deviations.
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Network Chart
A Network Chart, also known as a PERT chart is a project management tool used to schedule, organise and coordinate tasks within a project. The chart is a graphical representation of a project as a network diagram consisting of numbered nodes, either circles or rectangles representing events in the project linked by labeled directional lines that represent tasks in the project. The direction of the arrows on the lines indicates the sequence of tasks. Tasks that must be completed in sequence are called Dependant Tasks and those that are not dependent upon each other are called Parallel or Concurrent Tasks. This form of chart is often used in preference to the Gantt Chart because it clearly illustrates task dependencies.
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Noise
Noise is unexplained variability or any influence that prevents us from attaining identical measured values, or identical results, on repeated versions of an experiment. Whilst typically this may be due to the lack of control of a process, it is important when conducting Design of Experiments (DOE) analysis to take into consideration this noise. There are two key noise types to consider, experimental and observational.
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Nominal Group Technique
A group technique for prioritising ten or fewer activities, ideas or issues whereby individual importance is ranked into a teams final priorities.
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Non Value Added (NVA)
Non Value Added is a term used to describe those activities which consume time or resources but do not directly contribute towards meeting the customer’s requirements.
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Normal Distribution
A Normal Distribution is characterised by the smooth, bell shaped curve and is representative of the most frequently occurring value is in the middle of the range and the other probabilities can be seen to tail off symmetrically in both directions.
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np Chart
The np Chart is an attributes control chart and is used to show how the process, measured by the number of nonconforming items it produces, changes over time. The process attribute, or characteristic is described as yes/no, pass/fail, go/no go form. The Chart is used to determine if the process is stable and predictable.
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Null Hypothesis
A Null Hypothesis is the conclusion that two or more data sets or populations are statistically equal. According to the null hypothesis, any observed difference in samples is due to chance or sampling error.