Examines the model's parameters for stability constraints (e.g. stationary, invertibility, causality, etc.).
Syntax
ARMA_CHECK(mean, sigma, phi, theta)
 mean
 is the ARMA model longrun mean (i.e. mu).
 sigma
 is the standard deviation of the model's residuals/innovations.
 phi
 are the parameters of the AR(p) component model (starting with the lowest lag).
 theta
 are the parameters of the MA(q) component model (starting with the lowest lag).
Remarks
 The underlying model is described here.
 ARMA_CHECK checks the process for stability: stationarity, invertability, and causality.
 Using the Solver addin in Excel, you can specify the return value of ARMA_CHECK as a constraint to ensure a stationary ARMA model.
 The longrun mean can take any value or be omitted, in which case a zero value is assumed.
 The residuals/innovations standard deviation (sigma) must greater than zero.
 For the input argument  phi:
 The input argument is optional and can be omitted, in which case no AR component is included.
 The order of the parameters starts with the lowest lag.
 One or more parameters may have missing values or an error code (i.e. #NUM!, #VALUE!, etc.).
 The order of the AR component model is solely determined by the order of the last value in the array with a numeric value (vs. missing or error).
 For the input argument  theta:
 The input argument is optional and can be omitted, in which case no MA component is included.
 The order of the parameters starts with the lowest lag.
 One or more values in the input argument can be missing or an error code (i.e. #NUM!, #VALUE!, etc.).
 The order of the MA component model is solely determined by the order of the last value in the array with a numeric value (vs. missing or error).
Examples
Example 1:


Formula  Description (Result) 

=ARMA_CHECK($B$2,$B$3,$B$4,$B$5)  Is the model stable? (1) 
Files Examples
Related Links
References
 D. S.G. Pollock; Handbook of Time Series Analysis, Signal Processing, and Dynamics; Academic Press; Har/Cdr edition(Nov 17, 1999), ISBN: 125609906
 James Douglas Hamilton; Time Series Analysis; Princeton University Press; 1st edition(Jan 11, 1994), ISBN: 691042896
 Tsay, Ruey S.; Analysis of Financial Time Series; John Wiley & SONS; 2nd edition(Aug 30, 2005), ISBN: 0471690740
 Box, Jenkins and Reisel; Time Series Analysis: Forecasting and Control; John Wiley & SONS.; 4th edition(Jun 30, 2008), ISBN: 470272848
 Walter Enders; Applied Econometric Time Series; Wiley; 4th edition(Nov 03, 2014), ISBN: 1118808568
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