Background

Macroeconomic Advisers’ index of Monthly GDP (MGDP) is a monthly indicator of real aggregate output that is conceptually consistent with real Gross Domestic Product (GDP) in the NIPA’s. The consistency is derived from two sources. First, MGDP is calculated using much of the same monthly source data that is used in the calculation of GDP. Second, the method of aggregation to arrive at MGDP is similar to that for official GDP. The result is a monthly index whose variation at the quarterly frequency mimics that of official GDP, and whose intra-quarter variation is a meaningful and comprehensive measure of changes in output from month to month.

MGDP is calculated in two steps. First, a “raw index” is calculated from various monthly data, most of which are source data that BEA uses to calculate official quarterly GDP. When aggregated to the quarterly frequency, growth of this raw index is highly correlated with growth of official GDP, but the correlation is not perfect. In the second step, a monthly “residual” is calculated which reconciles the raw index with official GDP at the quarterly frequency. This reconciling monthly residual is selected so as to add as little new monthly variation to the raw index as possible. The result is a monthly index whose intra-quarter movement is determined primarily from the monthly source data and whose quarterly averages are nearly identical to official quarterly GDP.

All MA MGDP data and historical files are available to the public at no charge.

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Background on MA’s Monthly GDP Index

MA’s Monthly GDP Historical Data (Through August 2017)

Monthly GDP Release (Released September 28, 2017)

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