X12 ARIMA is a widely used software program for seasonal adjustment produced, distributed, and maintained by the U.S. Census Bureau. NumXL provides an intuitive interface with the program to help Excel users make forecasts and seasonal adjustments quickly and efficiently for economic and financial data. NumXL also offers users access to all raw files (input/output) that are generated in the process of data analysis.
In this tutorial, we’ll demonstrate the steps to compute the seasonally adjusted time series using NumXL functions in Excel.
(1) Select an empty cell to store the unique identifier of the model X12 ARIMA in Excel.
(2) Locate the X12 ARIMA icon in the toolbar (or menu in Excel 2003), and click on it.
(3) The dialog box X12 ARIMA in Excel pops up on the screen.
(4) Select the cell range for the input data, and pick a start date and frequency.
(5) Select the different options you wish to include in the regARIMA model and/or the seasonal adjustment filtering. When done, click on Apply to generate the native x12a script, and to display the model unique identifier in your sheet.
(6.1) Optionally, you may wish to examine the generated X12 ARIMA in Excelscript. To do so, click the button labeled "Open X-12 SPC File". The text file pops up on the screen in the Windows notepad application.
(6.2) Optionally, you may wish to run the x12a program and inspect the output. To do so, click the button labeled "Run X-12".
(6.3) Optionally, you may examine the raw output files by locating the button on the top-right corner of the dialog box and clicking "X12 output".
(7) When you're done, click "OK" to exit the wizard X12 ARIMA in Excel.
(8) To use the model in your worksheet, simply use the X12A* functions (e.g. X12ACOMP, X12AFORE, etc.) and reference the cell with the unique identifier in your function.