I have found a ready transaction about ARIMA forecasting into RapidMiner. I tried to apply it on my dataset. My dataset includes sales for 6 products, the temperature and date. I have sales for 2 years and I want to predict sales for the next Januray. So I made my new dataset like the old but I added the temperature an the date. So sales for every product is empty in order to predict it. Although i'm trying to predict with ARIMA , it says tha my dataset contains missing values which is true but why doesn't it predict them?
Also I want to ask, how have I got to change parameters of forecast validation and arima operators, in order to have a good prediction(step size, window size etc).
Thanks in advance.