What are the 'best' variables out there to forecast accurately GDP and inflation according to macro literature? What are the best variables out there to forecast accurately GDP and inflation according to macro literature?

I'd like to forecast the next quarter, not the long-run.

Some time-series ideas I gathered:


industry production
employment
important export-import partners production
business confidence indexes (e.g. INSEE)
You likely want to do this in real time which means you want to do a nowcasting. This is tricky because many economic series are revised, which means you also need real time data (what were the figures when released rather than what is known with hindsight). 

The Atlanta Federal Reserve Bank uses this approach in their GDP Now product. You should check out their methodology and inputs to get started on your attempt.


  The growth rate of real gross domestic product (GDP) measured by the
  U.S. Bureau of Economic Analysis (BEA) is a key metric of the pace of
  economic activity. It is one of the four variables included in the
  economic projections of Federal Reserve Board members and Bank
  presidents for every other Federal Open Market Committee (FOMC)
  meeting. As with many economic statistics, GDP estimates are released
  with a lag whose timing can be important for policymakers. For
  example, of the four scheduled 2014 release dates of an “advance” (or
  first) estimate of GDP growth, two are on the second day of a
  scheduled FOMC meeting with the other two on the day after the
  meeting. In preparation for FOMC meetings, policymakers have the Fed
  Board staff projection of this “advance” estimate at their disposal.
  These projections—available through 2008 at the Philadelphia Fed’s
  Real Time Data Center—have generally been more accurate than forecasts
  from simple statistical models. As stated by economists Jon Faust and
  Jonathan H. Wright in a 2009 paper, “by mirroring key elements of the
  data construction machinery of the Bureau of Economic Analysis, the
  Fed staff forms a relatively precise estimate of what BEA will
  announce for the previous quarter’s GDP even before it is announced.”
  
  The Atlanta Fed GDPNow model also mimics the methods used by the BEA
  to estimate real GDP growth. The GDPNow forecast is constructed by
  aggregating statistical model forecasts of 13 subcomponents that
  comprise GDP. Other private forecasters use similar approaches to
  “nowcast” GDP growth. However, these forecasts are not updated more
  than once a month or quarter, are not publicly available, or do not
  have forecasts of the subcomponents of GDP that add “color” to the
  top-line number. The Atlanta Fed GDPNow model fills these three voids.
  
  The BEA’s advance estimates of the subcomponents of GDP use publicly
  released data from the U.S. Census Bureau, U.S. Bureau of Labor
  Statistics, and other sources. Much of this data is displayed in the
  BEA’s Key Source Data and Assumptions table that accompanies the
  “advance” GDP estimate. GDPNow relates these source data to their
  corresponding GDP subcomponents using a “bridge equation” approach
  similar to the one described in a Minneapolis Fed study by Preston J.
  Miller and Daniel M. Chin. Whenever the monthly source data is not
  available, the missing values are forecasted using econometric
  techniques similar to those described in papers by James H. Stock and
  Mark W. Watson and Domenico Giannone, Lucrezia Reichlin, and David
  Small. A detailed description of the data sources and methods used in
  the GDPNow model is provided in an accompanying Atlanta Fed working
  paper.
  
  As more monthly source data becomes available, the GDPNow forecast for
  a particular quarter evolves and generally becomes more accurate. That
  said, the forecasting error can still be substantial just prior to the
  “advance” GDP estimate release. It is important to emphasize that the
  Atlanta Fed GDPNow forecast is a model projection not subject to
  judgmental adjustments. It is not an official forecast of the Federal
  Reserve Bank of Atlanta, its president, the Federal Reserve System, or
  the FOMC.