Thanks...but I cant find the formula for the adjustment.
Do you know what it is?
Well, I know the methodology. They use ARIMA (Auto-Regressive Integrated Moving Average), which in it's simplest form looks at the increase in employment / hiring each year that occurs during this period. It takes the average of that increase and uses THAT figure as a baseline. For example, let's say that:
1. Over the past 50 years, the average increase in employment for each November has been 200,000.
2. The average in every other month (not Nov, Dec, or Jan) has been 150,000.
Then we can surmise that, on average, approximately 50,000 people are added to the rolls each year thanks to the holidays. So when we seasonally adjust the data, we subtract that amount from the total.