This paper presents a comparison between similar types of American and Canadian forecasts of annual gross national product for an identical period (1960-69) using the same error measures. It was concluded that on mean, mean absolute, and mean square error bases, American forecasts were significantly more accurate than were the Canadian ones in predicting relative changes in their respective annual gross national products during the period 1960-69. Forecasters in both the United States and Canada were likely to have made the same types of errors on average in forecasting any given year. The general conclusion from the analysis of the errors seemed to suggest that a bias toward underestimating change may be less evident in the American gross national product forecasts than in those made in Canada. The negative mean errors were smaller, the percentage of underestimates was smaller, the covariance components of the mean square errors were larger, and the regression and test statistics were less suggestive. One of the more important points is that when "adjustments" of the predictions for differences in the basic nature of the economies are made, the conclusions as to differences in the "accuracy" of aggregate forecasts made in various countries may change a great deal. That is, conclusions as to differences in forecasting ability based solely on the comparison of "absolute accuracy" could be seriously misleading if the economies are not of approximately similar natures. The method of "adjustment" used here assumes that information as to the nature of the economies is contained in the past history of the variables to be forecast, so that a more worthwhile comparison is obtained when the respective judgmental sets are first "adjusted" by extrapolative predictions from these past actuals. Comparisons of the "relative" accuracy of forecasts showed that the American predictions of annual gross national product percentage changes had larger relative mean square errors than did the Canadian sets. That is, the American sets were only about as accurate as, and probably less accurate then, relative to extrapolative predictions. the forecasts made in Canada. The predictive efficiency of the Canadian gross national product forecasts relative to that of the extrapolative predictions was generally higher than that of the American predictions; the amount of autonomous information and available extrapolative information included was also somewhat higher. However, the extrapolative information actually used in forecasting was quite low in both countries, probably because of the essentially trendless nature of percentage changes in gross national product. [ABSTRACT FROM AUTHOR]