I am trying to figure out how to combine the input and output data into the ARX model and then apply it into the BIC (Bayesian Information Criterion) formula. Below is the code that I am currently working on:

for i=1:30; %% Set Model Order
    data=iddata(output,input,1);
    model = arx(data,[8 9 i]);
    yp = predict(model,data);
    ye = regress(data,yp{1,1}(1:4018,1));
    M(i) = var(yp);
    BIC(i)=(N+i*(log(N)-1))/(N-i)*log(M(i));
end

But it does not work. It keep on giving me an error something like below:

"The syntax "Data{...}" is not supported. Use the "getexp" command to extract individual experiments from an IDDATA object." I did not understand what does that mean. Can someone explain it to me and where do I do wrong on my piece of code?

Thanks in advance.

Sam.