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GARCHProcess
represents a generalized autoregressive conditionally heteroscedastic process of orders p and q, driven by a standard white noise.
represents a GARCH process with initial data init.
Details

- GARCHProcess is a discrete-time and continuous-state random process.
- A process x[t] is a GARCH process if the conditional mean Expectation[x[t]{x[t-1],…}]=0 and the conditional variance
given by Expectation[x[t]2{x[t-1],…}] satisfies the equation
.
- 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 GARCHProcess should have non-negative coefficients αi and βj and a positive coefficient κ.
- GARCHProcess[q,p] represents a GARCH process of orders q and p for use in EstimatedProcess and related functions.
- GARCHProcess can be used with such functions as RandomFunction, CovarianceFunction, and TimeSeriesForecast.
Examples
open allclose allBasic Examples (3)Summary of the most common use cases
Simulate a GARCHProcess:

https://wolfram.com/xid/0v51restwkdde-se76vc


https://wolfram.com/xid/0v51restwkdde-4iewur


https://wolfram.com/xid/0v51restwkdde-0lg2yf

Unconditional mean and variance of a weakly stationary process:

https://wolfram.com/xid/0v51restwkdde-b7z11p


https://wolfram.com/xid/0v51restwkdde-p99hv2


https://wolfram.com/xid/0v51restwkdde-t8vwwp


https://wolfram.com/xid/0v51restwkdde-lqhuff

The observations are uncorrelated but dependent:

https://wolfram.com/xid/0v51restwkdde-kd62j1

https://wolfram.com/xid/0v51restwkdde-2hau7

The squared values of the data are correlated:

https://wolfram.com/xid/0v51restwkdde-4m7h01

https://wolfram.com/xid/0v51restwkdde-ia2afh

Scope (13)Survey of the scope of standard use cases
Basic Uses (8)
Simulate an ensemble of paths:

https://wolfram.com/xid/0v51restwkdde-bi9bqw


https://wolfram.com/xid/0v51restwkdde-iv2byr

Simulate with arbitrary precision:

https://wolfram.com/xid/0v51restwkdde-big92j

Simulate a weakly stationary process with given initial values:

https://wolfram.com/xid/0v51restwkdde-qz5qde

https://wolfram.com/xid/0v51restwkdde-h1b72a

https://wolfram.com/xid/0v51restwkdde-l3esgs

https://wolfram.com/xid/0v51restwkdde-2vkjih

A non-weakly stationary process:

https://wolfram.com/xid/0v51restwkdde-849us2

https://wolfram.com/xid/0v51restwkdde-gq6qdl

https://wolfram.com/xid/0v51restwkdde-t1m0n8

An integrated GARCHProcess:

https://wolfram.com/xid/0v51restwkdde-bp9na8

https://wolfram.com/xid/0v51restwkdde-lqdz53

Explosive GARCHProcess:

https://wolfram.com/xid/0v51restwkdde-vdahex

https://wolfram.com/xid/0v51restwkdde-ptahjr

Such a process is not second-order stationary:

https://wolfram.com/xid/0v51restwkdde-b12vkp

Conditions for a GARCHProcess to be covariance-stationary:

https://wolfram.com/xid/0v51restwkdde-mutsnx

Region of second-order stationarity for a GARCHProcess[1,1]:

https://wolfram.com/xid/0v51restwkdde-vxckai


https://wolfram.com/xid/0v51restwkdde-i15pmg

Estimate a GARCHProcess:

https://wolfram.com/xid/0v51restwkdde-ppxlwo

https://wolfram.com/xid/0v51restwkdde-fsgvlg


https://wolfram.com/xid/0v51restwkdde-x957ms

Use maximum conditional likelihood:

https://wolfram.com/xid/0v51restwkdde-7kln61


https://wolfram.com/xid/0v51restwkdde-eirvpx
Find the forecast 20 steps ahead:

https://wolfram.com/xid/0v51restwkdde-dwbfbx

https://wolfram.com/xid/0v51restwkdde-qqw7j5

Find the mean squared errors of the forecast:

https://wolfram.com/xid/0v51restwkdde-zqnnuw

The forecasted states are equal to zero, hence the forecasted standard deviation bounds are:

https://wolfram.com/xid/0v51restwkdde-wux3zt
Plot the values with mean squared errors:

https://wolfram.com/xid/0v51restwkdde-pksy44

Process Slice Properties (5)
Moments of a weakly stationary GARCH of orders :

https://wolfram.com/xid/0v51restwkdde-u1d2k5

https://wolfram.com/xid/0v51restwkdde-6vu1p7


https://wolfram.com/xid/0v51restwkdde-1z4n08

Moment of a GARCH process with given initial conditions:

https://wolfram.com/xid/0v51restwkdde-4vo40k


https://wolfram.com/xid/0v51restwkdde-c76l3j


https://wolfram.com/xid/0v51restwkdde-djic8g


https://wolfram.com/xid/0v51restwkdde-nz2z6e


https://wolfram.com/xid/0v51restwkdde-vw5ylw


https://wolfram.com/xid/0v51restwkdde-diexmz

Region where kurtosis is defined:

https://wolfram.com/xid/0v51restwkdde-y5r0ud


https://wolfram.com/xid/0v51restwkdde-zmyzm4
Probability density function of the sample:

https://wolfram.com/xid/0v51restwkdde-s3nc1d

Use the Monte Carlo method to calculate NProbability for slice distribution:

https://wolfram.com/xid/0v51restwkdde-60em1m

https://wolfram.com/xid/0v51restwkdde-00997i

Calculate NExpectation:

https://wolfram.com/xid/0v51restwkdde-n91pf6

Compare to the second Moment:

https://wolfram.com/xid/0v51restwkdde-yzt5wc

Properties & Relations (3)Properties of the function, and connections to other functions
The values of a GARCHProcess are uncorrelated:

https://wolfram.com/xid/0v51restwkdde-8tryi9

Corresponding ARMAProcess:

https://wolfram.com/xid/0v51restwkdde-dfyenx

For a process with given initial values:

https://wolfram.com/xid/0v51restwkdde-z1tydk

Squared values of a GARCHProcess follow an ARMAProcess:

https://wolfram.com/xid/0v51restwkdde-rhmavw

https://wolfram.com/xid/0v51restwkdde-inxryx
CorrelationFunction and PartialCorrelationFunction of squared values:

https://wolfram.com/xid/0v51restwkdde-ntjl10

The corresponding ARMA process:

https://wolfram.com/xid/0v51restwkdde-x7lwn4

CorrelationFunction and PartialCorrelationFunction of the ARMA process:

https://wolfram.com/xid/0v51restwkdde-sc2499

Wolfram Research (2014), GARCHProcess, Wolfram Language function, https://reference.wolfram.com/language/ref/GARCHProcess.html.
Text
Wolfram Research (2014), GARCHProcess, Wolfram Language function, https://reference.wolfram.com/language/ref/GARCHProcess.html.
Wolfram Research (2014), GARCHProcess, Wolfram Language function, https://reference.wolfram.com/language/ref/GARCHProcess.html.
CMS
Wolfram Language. 2014. "GARCHProcess." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/GARCHProcess.html.
Wolfram Language. 2014. "GARCHProcess." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/GARCHProcess.html.
APA
Wolfram Language. (2014). GARCHProcess. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/GARCHProcess.html
Wolfram Language. (2014). GARCHProcess. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/GARCHProcess.html
BibTeX
@misc{reference.wolfram_2025_garchprocess, author="Wolfram Research", title="{GARCHProcess}", year="2014", howpublished="\url{https://reference.wolfram.com/language/ref/GARCHProcess.html}", note=[Accessed: 02-April-2025
]}
BibLaTeX
@online{reference.wolfram_2025_garchprocess, organization={Wolfram Research}, title={GARCHProcess}, year={2014}, url={https://reference.wolfram.com/language/ref/GARCHProcess.html}, note=[Accessed: 02-April-2025
]}