If GDP Lags, Watch the Economy GO

‘Gross output’ reflects the full value of the supply chain, and it portends much faster growth.

The Bureau of Economic Analysis will release its preliminary first-quarter growth figure on Friday. According to the Atlanta Fed consensus tracker, economists are predicting gross domestic product to have risen at a meager 2% annual rate. But a powerful behind-the-scenes indicator suggests the real rate may turn out to be significantly higher.

“Gross output,” or GO, reflects the full value of the supply chain—the business-to-business spending that moves all goods and services toward the final retail market. Based on my work...