Why I Tend To Use Year-to-Year Changes, Instead of Month-to-Month Changes

The following chart shows the (black line) annual percentage changes (January-to-January; February-February; etc.--shown in black) and the month-to-month (January to February, February-to-March; expressed as an annual percentage change--shown in yellow).  Month-to-month changes are much more volatile, and thus tend not to be representative of what's happening.  In this chart, I've used the percentage changes in payroll employment (which is a monthly series), seasonally adjusted.  I think looking at the year-to-year changes is a more accurate way of depicting how employment has been changing, and is a much clearer representation of those changes.

Of course, if your point is to point out how volatile month-to-month changes are, that's different.  Usually, my concern is to capture more clearly whatever underlying patterns exist.