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ARMA

Create an Autoregressive Moving Average (ARMA) Process


Description

Sets up the necessary backend for the ARMA process.

Usage

ARMA(ar = 1, ma = 1, sigma2 = 1)

Arguments

ar

A vector or integer containing either the coefficients for phi's or the process number p for the Autoregressive (AR) term.

ma

A vector or integer containing either the coefficients for theta's or the process number q for the Moving Average (MA) term.

sigma2

A double value for the standard deviation, sigma, of the ARMA process.

Details

A variance is required since the model generation statements utilize randomization functions expecting a variance instead of a standard deviation like R.

Value

An S3 object with called ts.model with the following structure:

process.desc

AR x p, MA x q

theta

sigma

plength

Number of Parameters

print

String containing simplified model

obj.desc

y desc replicated x times

obj

Depth of Parameters e.g. list(c(length(ar),length(ma),1) )

starting

Guess Starting values? TRUE or FALSE (e.g. specified value)

Note

We consider the following model:

X_t = ∑_{j = 1}^p φ_j X_{t-j} + ∑_{j = 1}^q θ_j \varepsilon_{t-j} + \varepsilon_t

, where \varepsilon_t is iid from a zero mean normal distribution with variance σ^2.

Author(s)

James Balamuta

Examples

# Create an ARMA(1,2) process
ARMA(ar=1,2)
# Creates an ARMA(3,2) process with predefined coefficients.
ARMA(ar=c(0.23,.43, .59), ma=c(0.4,.3))

# Creates an ARMA(3,2) process with predefined coefficients and standard deviation
ARMA(ar=c(0.23,.43, .59), ma=c(0.4,.3), sigma2 = 1.5)

simts

Time Series Analysis Tools

v0.1.1
AGPL-3 | file LICENSE
Authors
Stéphane Guerrier [aut, cre, cph], James Balamuta [aut, cph], Roberto Molinari [aut, cph], Justin Lee [aut], Yuming Zhang [aut], Wenchao Yang [ctb], Nathanael Claussen [ctb], Yunxiang Zhang [ctb], Christian Gunning [cph], Romain Francois [cph], Ross Ihaka [cph], R Core Team [cph]
Initial release
2019-07-21

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