Seasonal adjustment of real aggregates

This article examines the seasonal characteristics of real aggregates in Peru, focusing on overall Gross Domestic Product (GDP) and its sectors from 1991 to 1996. The study seeks to determine whether seasonal adjustment of GDP should be performed using the direct method—which adjusts the series as a whole—or the indirect method—which sums the seasonally adjusted sectoral GDPs. The X-11-ARIMA methodology is used to seasonally adjust the time series and determine the presence of seasonality, employing both graphical analysis and various statistical tests. The results indicate that some sectors, such as the agricultural sector and government, exhibit stable seasonality and are suitable for adjustment, while others, such as mining and construction, are conditionally suitable due to the influence of irregular components. The main implication of the study is that seasonal adjustment using the direct method is preferable given its superior smoothing performance and greater effectiveness in identifying patterns, which represents a key consideration for economic policy formulation and macroeconomic analysis. (Abstract and audio: Department of Economic Publications)