Economic growth slowed to a crawl in the first three months of this year, but a rebound is projected for the second quarter, according to The Capital Spectator’s median econometric nowcast. GDP is expected to rise 2.8% during the April-through-June period (real seasonally adjusted annual rate). This is an initial estimate that uses limited Q2 data and so the projection is a preliminary review that will be updated several times in the weeks ahead as new economic indicators are published and existing data are revised. The final nowcast for the quarter will be published shortly ahead of the official Q2:2014 GDP report. The US Bureau of Economic Analysis (BEA) is scheduled to release its “advance” Q2 estimate on July 30, 2014.

Looking backward for a moment, let’s recognize that the final nowcast for Q1 reflected a substantially stronger economy compared with the official GDP data. Rather than the implied 2.4% advance, the BEA reported a tepid 0.1% rise in this year’s Q1 GDP. Nonetheless, the fact that the Q1 projection was well above the initial GDP estimate from the government suggests that economic activity, while struggling in the early months of this year, still had enough forward momentum to keep the expansion alive.

As for looking ahead, here’s how The Capital Spectator’s initial Q2 nowcast compares with recent history and several forecasts from other sources:

Next, let’s review the individual nowcasts that are used to calculate the median estimate:

As new nowcasts are published in the weeks ahead, the chart below will track the updates for context on assessing how the business cycle is evolving in the current quarter.

Finally, here’s a brief profile for each of The Capital Spectator’s GDP nowcast methodologies:

R-4: This estimate is based on a multiple regression in R of historical GDP data vs. quarterly changes for four key economic indicators: real personal consumption expenditures (or real retail sales for the current month until the PCE report is published), real personal income less government transfers, industrial production, and private non-farm payrolls. The model estimates the statistical relationships from the early 1970s to the present. The estimates are revised as new data is published.

R-10: This model also uses a multiple regression framework based on numbers dating to the early 1970s and updates the estimates as new data arrives. The methodology is identical to the 4-factor model above, except that R-10 uses additional factors—10 in all—to nowcast GDP. In addition to the data quartet in the 4-factor model, the 10-factor nowcast also incorporates the following six series: ISM Manufacturing PMI Composite Index, housing starts, initial jobless claims, the stock market (Wilshire 5000), crude oil prices (spot price for West Texas Intermediate), and the Treasury yield curve spread (10-year Note less 3-month T-bill).

ARIMA GDP: The econometric engine for this nowcast is known as an autoregressive integrated moving average. This ARIMA model uses GDP’s history, dating from the early 1970s to the present, for anticipating the target quarter’s change. As the historical GDP data is revised, so too is the nowcast, which is calculated in R via the “forecast” package, which optimizes the parameters based on the data set’s historical record.

ARIMA R-4: This model combines ARIMA estimates with regression analysis to project GDP data. The ARIMA R-4 model analyzes four historical data sets: real personal consumption expenditures, real personal income less government transfers, industrial production, and private non-farm payrolls. This model uses the historical relationships between those indicators and GDP for projections by filling in the missing data points in the current quarter with ARIMA estimates. As the indicators are updated, actual data replaces the ARIMA estimates and the nowcast is recalculated.

VAR 4: This vector autoregression model uses four data series in search of interdependent relationships for estimating GDP. The historical data sets in the R-4 and ARIMA R-4 models noted above are also used in VAR-4, albeit with a different econometric engine. As new data is published, so too is the VAR-4 nowcast. The data sets range from the early 1970s to the present, using the “vars” package in R to crunch the numbers.

ARIMA R-NIPA: The model uses an autoregressive integrated moving average to estimate future values of GDP based on the datasets of four primary categories of the national income and product accounts (NIPA): personal consumption expenditures, gross private domestic investment, net exports of goods and services, and government consumption expenditures and gross investment. The model uses historical data from the early 1970s to the present for anticipating the target quarter’s change. As the historical numbers are revised, so too is the estimate, which is calculated in R via the “forecast” package, which optimizes the parameters based on the data set’s historical record.