Expected a string scalar or character vector for the parameter name

When I try to run code for "Forecast Multiplicative ARIMA Model" example (https://es.mathworks.com/help/econ/forecast-airline-passenger-counts.html) I get the message "expected a string scalar or character vector for the parameter name".

This part works fine:

load(fullfile(matlabroot,'examples','econ','Data_Airline.mat'))
y = log(Data);
T = length(y);
Mdl = arima('Constant',0,'D',1,'Seasonality',12,...
    'MALags',1,'SMALags',12);
EstMdl = estimate(Mdl,y);

but when I try:

[yF,yMSE] = forecast(EstMdl,60,y);

then i get above mentioned message.

[Adam Danz]

Could you share the full copy-pasted error message?

[Adis Hamzic]

Adam, here is complete code and error:

>> load(fullfile(matlabroot,'examples','econ','Data_Airline.mat'))

>> y = log(Data);

T = length(y);

Mdl = arima('Constant',0,'D',1,'Seasonality',12,...

'MALags',1,'SMALags',12);

EstMdl = estimate(Mdl,y);

ARIMA(0,1,1) Model Seasonally Integrated with Seasonal MA(12):

---------------------------------------------------------------

Conditional Probability Distribution: Gaussian

Standard t

Parameter Value Error Statistic

----------- ----------- ------------ -----------

Constant 0 Fixed Fixed

MA{1} -0.377162 0.0667944 -5.64661

SMA{12} -0.572378 0.0854395 -6.69923

Variance 0.00126337 0.00012395 10.1926

>> [yF,yMSE] = forecast(EstMdl,60,y);

Expected a string scalar or character vector for the parameter name.

Answer 1

[Adam Danz]

The help section of the forecast() function shows that there are two inputs and then you can enter optional parameter-value pairs.

help forecast
% [Y,YMSE,V] = forecast(Mdl, numPeriods, param1,val1,param2,val2,...)

If you're checking the predictive performance of the model, the paramter name you might be missing is 'Y0'.

[yF,yMSE] = forecast(EstMdl,60,'Y0',y);
%                               **

But check the other name-value pairs to be sure about what you're specifying here.

Recent version of matlab:

https://www.mathworks.com/help/econ/arima.forecast.html#namevaluepairs

Older versions of matlab

https://www.mathworks.com/help/releases/R2017b/econ/arima.forecast.html#bs679gg-4

[Adis Hamzic]

Thank you Adam. Now it works.