SPCEWMA-class {spcadjust}

EWMA Charts

Description

Class extending SPCChart with a basic EWMA charts implementation.

Details

Let Y_t, t=1,2,\dots be the updates from the data model. Then the EWMA chart is given by Q_0=0 and

Q_t=lambda Y_t+(1-lambda) Q_{t-1}

Slots

model

The data model. The data model should center the in-control updates such that they have mean 0.

lambda

The smoothing constant, 0<lambda<=1.

Examples

X <-  rnorm(1000)
chart <- new("SPCEWMA",model=SPCModelNormal(Delta=0),lambda=0.8)
## Not run: 
SPCproperty(data=X,nrep=10,chart=chart,
            property="calARL",params=list(target=100))
SPCproperty(data=X,nrep=10,chart=chart,
            property="calhitprob",params=list(target=0.05,nsteps=1e3))

## End(Not run)
SPCproperty(data=X,nrep=10,chart=chart,
            property="ARL",params=list(threshold=3))
SPCproperty(data=X,nrep=10,chart=chart,
            property="hitprob",params=list(threshold=3,nsteps=1e3))
#increase the number of repetitions nrep for real applications.