Exponentially Weighted Moving Average Chart Page 6

ST 435/535

Statistical Methods for Quality and Productivity Improvement / Statistical Process Control

Moving Average Control Chart

The EWMA chart is easy to set up recursively, since the current value

of z depends on only the current x and the previous z.

However, because it is a (exponentially) weighted average of all past

observations, it is impacted, at least a little, by the entire past.

An alternative, with ﬁnite memory, is the moving average (MA) chart

with span w , based on the unweighted average

x + x

+ x

m =

i = w w + 1

6 / 8

Cusum and Moving Average Control Charts

Moving Average Control Chart

0 votes

Parent category: Business