An Approach to the Determinants of the Agricultural Output Dynamics in the USA - The Agricultural Economics of the 21st Century - page 16

Table 2.3 Results obtained with time series econometric techniques, considering the function of
production model extended with others variables (linear model obtained with logarithms), for the
agricultural output in the period 1961-2012
Model Prais-Winsten

Constant 6.425*

(3.390)
[0.002]

Agriculture value added per worker (constant 2005 US$) 0.598*

( 3.650)
[0.001]

Employment in agriculture (% of total employment)
Inflation, consumer prices (annual %)

0.172*
(2.870)
[0.008]

Breusch-Pagan/Cook-Weisberg test for heteroskedasticity 0.010

[0.909]

Ramsey RESET test using powers of the fitted values 3.240*

[0.040]

LM test for autoregressive conditional heteroskedasticity (ARCH) 0.732

[0.392]

Note : *Statistically significant at 5 %

extending the original model base in the well-known Cobb-Douglas function of
production.
Table 2.3 reveals that from all the additional independent variables, despite
agricultural employment and productivity, only the inflation of consumer price
rates improve the model and show a positive influence towards agricultural output,
with a coefficient statistically significant of 0.172. This shows the interrelationship
between all the economies of the USA. All the results of the statistical tests reveal
that there are no problems with the autocorrelation and with the heteroskedasticity,
but the Ramsey RESET test, using powers of the fitted values, maintains evidence
of a lack in independent variables, which may be an interesting finding for future
research.
Finally, referring that all the results presented in the three tables are in agreement
with each other and with the data description made in the previous section.

Conclusions
The preoccupation with climate changes, the environment, sustainability,
water management, the consequences of agricultural policies in society, the
changes in social patterns, and the design of adjusted agricultural policies are
the order of the day in many countries, namely in developed countries, when
we speak about the agricultural economics in the context of globalized

(continued)