Close to the midpoint of every month, and about a week after the major individual retail chains issue their monthly reports on aggregate and same-store sales, the U.S. Commerce Department releases its survey on total retail sales for the past month. It is one of the more closely watched of the periodic economic reports, since it chronicles spending by consumers, and consumers account for some 70% of a nation’s output of goods and services—or the Gross Domestic Product.

The retail sales data are given two ways: aggregate sales and total sales excluding autos. It is the former that is the headline number.

The major components of the report include such items as the aforementioned U.S. car and parts sales, filling station sales, expenditures at restaurants and bars, spending at electronics and appliance stores, and sales at food stores, garden supplies retailers, furniture retailers, and providers of health and personal care products. It is a broad composite of the nation’s spending for the past month. The month-to-month changes are given in percentage terms.

Once the report is issued, along with revisions for the prior month or two, the economic pundits are quick to revisit their GDP forecasts for the current quarter. The retail performance is so critical that major rethinking of GDP assumptions often take place.

Of course, sometimes the report needs to be taken with the proverbial grain of salt, as overreactions in the financial press can take place, especially if such exogenous effects, as stormy weather, are not deftly noted. Still, it is a report worth watching and duly acting upon, once all the immediate noise passes.