I have a data set (about 60 observations for each variable) for monthly operating income for a Japanese company denoted in EUR, USD, and JPY, and their respective currencies. I believe there is linear relationship between the currencies and the respective operating income denoted in the currencies. However, the first differences in operating income and currencies are random.
What is the best way to forecast the exposure of the future short-term month's operating income?
I have translated the foreign income to JPY and added them together with their domestic operating income, and then use moving average, weighted moving average and trend line to forecast the next month (into the future).
I have also used the first differences/increments of the operating incomes and their respective currencies to make them stationary, and to find the regression and coefficient. However, I don't know how to use the results to forecast.
Are there any other models that produce better outcomes for this fairly limited sample set?