Findings
This study estimate purchasing power parity (PPP) models of the US Dollar-Pound Sterling based on data from 1861-2014, after which the statistical accuracy and economic value of these forecasts are compared. This study finds that 1) the estimated model beats a random walk model in-sample and 2) that both the accuracy and value of out-of-sample forecasts fall as the forecast horizon increases.
Model developed
The developed models predict estimated future changes in the USD-GBP 1, 4, 8, 12 and 16 years ahead based on gaps between the spot and PPP-implied exchange rate. Table 1 and diagram 1 below show that all five models are statistically significant and have intuitive coefficients: an increase in the fundamental exchange rate (ft) over the spot exchange rate (st) leads to a future increase in the spot exchange rate across all forecasting horizons.
Table 1: model findings
Diagram 1: coefficients and forecast errors across different forecast horizons
To ensure congruency all five models were estimated using heteroskedasticity and autocorrelation-consistent standard errors. Except for the model forecasting four years ahead, then the parameter stability of other forecast horizons was deemed sufficiently stable to use for forecasting.
Forecast accuracy and value
The statistical accuracy and economic value of the estimated models were analyzed across the different forecasting horizons. The economic value of forecasts was examined using the directional accuracy and time value-adjusted root mean squared forecast error (RMSFE), and a stylized finding is that both the statistical accuracy and economic value of the estimated models decrease as the forecasting horizon increases.
Read the full paper here: http://bit.ly/2qYoxdl