WOLFRAM

MAProcess[{b1,,bq},v]

represents a moving-average process of order q with normal white noise variance v.

MAProcess[{b1,,bq},Σ]

represents a vector MA process with multinormal white noise covariance matrix Σ.

MAProcess[{b1,,bq},v,init]

represents an MA process with initial data init.

MAProcess[c,]

represents an MA process with a constant c.

Details

  • MAProcess is also known as a finite impulse response (FIR) filter.
  • MAProcess is a discrete-time and continuous-state random process.
  • The MA process is described by the difference equation , where is the state output, is white noise input, is the shift operator, and the constant c is taken to be zero if not specified.
  • The initial data init can be given as a list {,y[-2],y[-1]} or a single-path TemporalData object with time stamps understood as {,-2,-1}.
  • A scalar MA process should have real coefficients bi and c, and a positive variance v.
  • An -dimensional vector MA process should have real coefficient matrices bi of dimensions ×, real vector c of length , and the covariance matrix Σ should be symmetric positive definite of dimensions ×.
  • The MA process with zero constant has transfer function where:
  • scalar process
    vector process; is the × identity matrix
  • MAProcess[tproc,q] for a time series process tproc gives an MA process of order q such that the series expansions about zero of the corresponding transfer functions agree up to degree q.
  • Possible time series processes tproc include ARProcess, ARMAProcess, and SARIMAProcess.
  • MAProcess[q] represents a moving-average process of order q for use in EstimatedProcess and related functions.
  • MAProcess can be used with such functions as CovarianceFunction, RandomFunction, and TimeSeriesForecast.

Examples

open allclose all

Basic Examples  (3)Summary of the most common use cases

Simulate an MA process:

Out[1]=1
Out[2]=2

Covariance function:

Out[1]=1
Out[2]=2

Correlation function:

Out[1]=1

Partial correlation function:

Out[2]=2

Scope  (37)Survey of the scope of standard use cases

Basic Uses  (11)

Simulate an ensemble of paths:

Out[1]=1
Out[2]=2

Simulate with given precision:

Out[1]=1

Simulate a first-order scalar process:

Sample paths for positive and negative values of the parameter:

Out[2]=2

Initial values do not influence the process values:

Out[4]=4

Simulate a two-dimensional process:

Create a 2D sample path function from the data:

The color of the path is the function of time:

Out[3]=3

Create a 3D sample path function with time:

The color of the path is the function of time:

Out[5]=5

Simulate a three-dimensional process:

Create a sample path function from the data:

The color of the path is the function of time:

Out[3]=3

Estimation:

Out[1]=1

Compare the sample covariance functions with the one of the estimated process:

Out[2]=2

Use TimeSeriesModel to automatically find orders:

Out[3]=3
Out[4]=4

Compare the sample covariance functions with the best time series model:

Out[5]=5

Find maximum likelihood estimator:

Fix the constant and the variance and estimate the remaining parameters:

Out[3]=3

Plot the log-likelihood function together with the position of the estimated parameters:

Out[4]=4

Estimate a vector moving-average process:

Out[2]=2

Compare covariance functions for each component:

Out[3]=3

Forecast future values:

Out[1]=1

Show the forecast path:

Out[2]=2

Plot the data and the forecasted values:

Out[3]=3

Find a forecast for a vector-valued time series process:

Find the forecast for the next 10 steps:

Out[2]=2

Plot the data and the forecast for each component:

Out[3]=3

Covariance and Spectrum  (6)

Correlation function exists in closed form:

Out[1]=1
Out[2]=2

Closed form of the partial correlation function for the first order:

Out[1]=1

Covariance matrix:

Covariance matrix of an MAProcess is symmetric multidiagonal:

Correlation matrix:

Covariance function for a vector-valued process:

Power spectral density:

Out[1]=1
Out[2]=2

Vector MAProcess:

Stationarity and Invertibility  (4)

MAProcess is weakly stationary for any choice of parameters:

Out[1]=1

For a vector process:

Out[2]=2

Check if a time series is invertible:

Out[2]=2

For a vector process:

Out[3]=3

Find invertible representation for a moving-average process:

Out[1]=1
Out[2]=2

The moments are being conserved:

Out[3]=3
Out[4]=4

Find invertibility conditions:

Out[1]=1
Out[2]=2

Find conditions for higher order:

Out[3]=3
Out[4]=4

Estimation Methods  (6)

The available methods for estimating an MAProcess:

Out[3]=3

Compare log likelihoods:

Out[4]=4

Method of moments allows following solvers:

Out[3]=3

This method allows for fixed parameters:

Out[4]=4

Some relations between parameters are also permitted:

Out[5]=5

Maximum conditional likelihood method allows following solvers:

Out[3]=3

This method allows for fixed parameters:

Out[4]=4

Some relations between parameters are also permitted:

Out[5]=5

Maximum likelihood method allows following solvers:

Out[3]=3

This method allows for fixed parameters:

Out[4]=4

Some relations between parameters are also permitted:

Out[5]=5

Spectral estimator allows to specify windows used for PowerSpectralDensity calculation:

Out[2]=2

Spectral estimator allows following solvers:

Out[4]=4

This method allows for fixed parameters:

Out[5]=5

Some relations between parameters are also permitted:

Out[6]=6

Minimum prediction method:

Out[2]=2

This method allows for fixed parameters:

Out[3]=3

Process Slice Properties  (5)

Single time SliceDistribution:

Out[1]=1

Multiple time slice distributions:

Out[2]=2
Out[3]=3

Slice distribution of a vector-valued time series:

Out[4]=4

First-order probability density function:

Out[1]=1
Out[2]=2

Stationary mean and variance:

Out[3]=3
Out[4]=4

Compare with the density function of a normal distribution:

Out[5]=5
Out[6]=6

Compute the expectation of an expression:

Out[1]=1

Calculate a probability:

Out[2]=2

Skewness and kurtosis are constant:

Out[1]=1
Out[2]=2

Moment of order r:

Out[1]=1

Generating functions:

Out[2]=2
Out[3]=3

CentralMoment and its generating function:

Out[4]=4
Out[5]=5

FactorialMoment has no closed form for symbolic order:

Out[6]=6
Out[7]=7

Cumulant and its generating function:

Out[8]=8
Out[9]=9

Representations  (5)

Approximate an AR process with an MA process of order 5:

Out[1]=1

Compare the covariance function for the original and the approximate processes:

Out[2]=2

Approximate a vector process:

Out[3]=3

Approximate an ARMA process with an MA process:

Out[1]=1
Out[2]=2

Compare sample paths:

Out[3]=3

Approximate a SARIMA process with an MA process:

Out[1]=1

Compare sample paths:

Out[2]=2

TransferFunctionModel representation:

Out[1]=1

For a vector-valued process:

Out[2]=2

StateSpaceModel representation:

Out[1]=1

For a vector-valued process:

Out[2]=2

Applications  (1)Sample problems that can be solved with this function

Consider the following time series data and determine whether it is adequately modeled by an MAProcess:

Out[3]=3

The correlation function drops off after lag 3. This is evidence of an MAProcess[3]:

Out[4]=4

The partial correlation alternates and dampens slowly, which also indicates an MAProcess:

Out[5]=5

Fit an MAProcess[3] model to the data:

Out[6]=6

Find residuals between the data and the model:

Out[7]=7
Out[9]=9

Test if residuals are normal white noise:

Out[10]=10
Out[11]=11

Properties & Relations  (5)Properties of the function, and connections to other functions

MAProcess is a special case of an ARMAProcess:

Out[1]=1
Out[2]=2
Out[3]=3

MAProcess is a special case of an ARIMAProcess:

Out[1]=1
Out[2]=2
Out[3]=3

MAProcess is a special case of a FARIMAProcess:

Out[1]=1
Out[2]=2
Out[3]=3

MAProcess is a special case of a SARMAProcess:

Out[1]=1
Out[2]=2
Out[3]=3

MAProcess is a special case of a SARIMAProcess:

Out[1]=1
Out[2]=2
Out[3]=3

Possible Issues  (3)Common pitfalls and unexpected behavior

ToInvertibleTimeSeries does not always exist:

Out[1]=1

There are zeros of the TransferFunctionModel on the unit circle:

Out[2]=2
Out[3]=3

The method of moments may not find a solution in estimation:

Out[2]=2

Use a different solver:

Out[3]=3

Minimum prediction error estimation method does not allow repeated parameters:

Out[2]=2

Use a different method:

Out[3]=3

Neat Examples  (2)Surprising or curious use cases

Simulate a three-dimensional MAProcess:

Out[2]=2

Simulate paths from an MA process:

Take a slice at 50 and visualize its distribution:

Plot paths and histogram distribution of the slice distribution at 50:

Out[4]=4
Wolfram Research (2012), MAProcess, Wolfram Language function, https://reference.wolfram.com/language/ref/MAProcess.html (updated 2014).
Wolfram Research (2012), MAProcess, Wolfram Language function, https://reference.wolfram.com/language/ref/MAProcess.html (updated 2014).

Text

Wolfram Research (2012), MAProcess, Wolfram Language function, https://reference.wolfram.com/language/ref/MAProcess.html (updated 2014).

Wolfram Research (2012), MAProcess, Wolfram Language function, https://reference.wolfram.com/language/ref/MAProcess.html (updated 2014).

CMS

Wolfram Language. 2012. "MAProcess." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2014. https://reference.wolfram.com/language/ref/MAProcess.html.

Wolfram Language. 2012. "MAProcess." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2014. https://reference.wolfram.com/language/ref/MAProcess.html.

APA

Wolfram Language. (2012). MAProcess. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/MAProcess.html

Wolfram Language. (2012). MAProcess. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/MAProcess.html

BibTeX

@misc{reference.wolfram_2025_maprocess, author="Wolfram Research", title="{MAProcess}", year="2014", howpublished="\url{https://reference.wolfram.com/language/ref/MAProcess.html}", note=[Accessed: 02-June-2025 ]}

@misc{reference.wolfram_2025_maprocess, author="Wolfram Research", title="{MAProcess}", year="2014", howpublished="\url{https://reference.wolfram.com/language/ref/MAProcess.html}", note=[Accessed: 02-June-2025 ]}

BibLaTeX

@online{reference.wolfram_2025_maprocess, organization={Wolfram Research}, title={MAProcess}, year={2014}, url={https://reference.wolfram.com/language/ref/MAProcess.html}, note=[Accessed: 02-June-2025 ]}

@online{reference.wolfram_2025_maprocess, organization={Wolfram Research}, title={MAProcess}, year={2014}, url={https://reference.wolfram.com/language/ref/MAProcess.html}, note=[Accessed: 02-June-2025 ]}