Tools

Concepts

Control Chart Properties

Rational Subgroups

Defining Control Limits

Short Run Techniques

Interpretation & Calculations

Attributes Charts

X-Bar / Range Charts

X-Bar / Sigma Charts

Individual-X Charts

Moving Average Charts

Multivariate Control Charts

Histograms, Process Capability

Autocorrelation Charts

Measurement Systems Analysis

Applications

Getting Started with SPC

Key Success Factors for the Implementation of SPC

How to Study Process Capability

Multiple Steam Processes

Analysis of Batch Processes

SPC to Improve Quality, Reduce Cost

Struggling with Independence

SPC Analysis of MLB Home Runs

Use Of SPC To Detect Process Manipulation

Using Data Mining and Knowledge Discovery With SPC

EWMA Statistic

The exponentially weighted moving average of the current subgroup, as used in a standard EWMA Chart.

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where:

λ is the value of the Weighting Factor (user defined; See When to Use EWMA Charts )

x-bart is the subgroup average, for the current subgroup at time t (or the current observation, if subgroup size is one (n=1)).

the value of z at time zero (zo) is either a Target value or the overall Average of the selected subgroups (user defined).

See also:

EWMA Control Limits

Interpreting an EWMA Chart

Learn more about the SPC principles and tools for process improvement in Statistical Process Control Demystified (2011, McGraw-Hill) by Paul Keller, in his online SPC Concepts short course (only $39), or his online SPC certification course ($350) or online Green Belt certification course ($499).