TRAMO/SEATS method in seasonal adjustment: An application on gross domestic product and its main items

TRAMO/SEATS is a two-stage seasonal adjustment method including, TRAMO (Time series Regression with Arima noise, Missing values, and Outliers) and SEATS (Signal Extraction in ARIMA Time Series). In the study TRAMO used for estimation and forecasting of a regression model is applied by considering non-stationary error term (ARIMA). Program estimates missing values in six macro economic time series featured general characteristic of Turkish economy with interpolation, specifies and adjusts outliers in different type. Procedure calendar effect correction is also aplied.The aim of this study is to obtain comparable results by adjustment calendar effects determined before seasonality in series for some macro economic values in Turkey.In the application part, TRAMO precedure was used for time series belonging to the values of GDP, Resident Household Consumption, Governmental final consumption expenditure, Gross fixed capital formation, Constant values of export and Import of goods and services. The analyzed series is for three months and covers years between 1998 to 2010. Crises in related series determined and adjusted as outlier effects. Besides, it is concluded that calendar effects covering holidays should take into consideration in order to compare between the terms properly.?Key Words:1.Tramo2.Outliers3.Calendar effects4.Seasonality