I wasn't asking about ARIMA, I was just using that as an example of what I was talking about. I myself don't have a model, I measure what price action is currently doing. I can do this in as few as 9 data points but something in the mid teens is better.Quote from ssrrkk:
Like I said I haven't used ARIMA models so I can't help you there. In general, you can get confidence levels on your parameter estimates for your model and that should tell you whether you have a good estimate or bad, not a universal cutoff on the number of training points.
So, how many data points does YOUR model require?
