Many economic indicators follow predictable patterns at the same time each year. Equipment financing volumes, for example, tend to be higher in December and lower in January due to recurring factors like budget cycles, tax deadlines, and end-of-year purchasing. These recurring patterns are called seasonality.
Seasonal adjustment is a statistical process that removes these predictable patterns from the data, allowing for analysis of underlying trends and developments. Without seasonal adjustment, a predictable year-end increase in NBV could obscure underlying demand weakness. Conversely, a typical December-to-January slowdown, which occurs every year, might mask underlying strength.
The CFI is seasonally adjusted using the X-13ARIMA-SEATS program, developed and maintained by the U.S. Census Bureau. This is the same methodology used by most federal statistical agencies to adjust national economic indicators.
The release reports both seasonally adjusted and non-seasonally adjusted figures. Seasonally adjusted data are best for evaluating month-to-month changes and trends, and identifying underlying recent industry and economy-wide developments. The non-seasonally adjusted figures are best used for comparing the same month across different years.