Centre county Pennsylvania, USA | Simple regression of most recent 35 years of NASS reported national corn production and national corn yield (chart) shows that 91% of national corn production is explained by national corn yield (Rsquared = 0.91). Trend line from that regression predicts (forecasts) the expected corn production, in billion bushels, as:
expected national corn production = 0.1029 x national corn yield - 3.8073;
and,
standard deviation national corn production = 0.725
Using 2015 national corn yield of 167.5 (forecasted in the Sep 11 2015 NASS Crop Production report) in this crop production model, gives expected 2015 national corn production of 13.428 billion bushels. That's 172 million bushels below the Sep 11 2015 NASS forecast of 13.6 billion bushels, but the 172 million bushel difference is well within the model's standard deviation.
That's remarkable model performance, considering that the model does not use planted, or harvested, acres to forecast production. When the model is used to forecast national harvested acres:
national harvested corn acres = national corn production / national corn yield,
it forecasts 2015 national harvested corn acres = 13.428/167.5 = 80.167 million acres.
 (corn_production_yield_correlation.png)
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 corn_production_yield_correlation.png (63KB - 425 downloads)
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Forecasting national corn production
