How to pull out aic from arima

Greetings-

I have been digging through the help and my search has failed me. I am running a aimple arima on a small matrix [30x99], one column at a time and I'd like to pull the aic. The code I am using is pretty much stright from the examples here.

totalsColumn = normM(:,99);
categoryModel = arima(2,1,1);
categoryFit = estimate(categoryModel,totalsColumn);
results = summarize(categoryModel)

What I am reading says summarize should output a few things including "aic = -something" but I get:

results = 

arima with properties:

Description: "ARIMA(2,1,1) Model (Gaussian Distribution)"
Distribution: Name = "Gaussian"
P: 3
D: 1
Q: 1
Constant: NaN
AR: {NaN NaN} at lags [1 2]
SAR: {}
MA: {NaN} at lag [1]
SMA: {}
Seasonality: 0
Beta: [1×0]
Variance: NaN

and not what is shown on the page at https://www.mathworks.com/help/econ/arima.summarize.html

Also using value - aic(categoryModel) (or categoryFit, just gives me an error of:

Undefined function 'aic' for input arguments of type 'arima'.

Error in projectW100Norm (line 17)
value = aic(categoryModel)

I have both the economic toobox and the system identification toolbox downloaded and added.

I just want to pull out the aic. I know that it is shown in the economic modeler app, but I'd like to pull it for my code.

Thank you in advance for any help.

Answer 1

[William Rose]

@Amanda Willard Sauer,

You only get the AIC for an estimated model.

In the code you posted, you are looking at the results for the un-estimated model "CategoryModel".

Look at categoryFit instead.

categoryFit = estimate(categoryModel,totalsColumn);
results = summarize(categoryFit)
disp(results.AIC)

Try it. Good luck.

[Amanda]

Absolutely perfect. Thank you.

[William Rose]

@Amanda Willard Sauer, you're welcome.