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capri:concept:refrun [2011/04/11 08:31] – created 131.220.212.14capri:concept:refrun [2011/10/04 08:17] – wolfgangb
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 +      <H2>Reference run</H2>
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 +      <H3>Overview</H3>
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 +      <TABLE padding="20px"><TR><TD>
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 +      <P>The reference run or baseline serves as a reference point for ex-ante impact analysis
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 +      with CAPRI. It reflects the most probable development in agricultural markets
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 +      from global to regional scale for 8-10 year time horizon, at the current legislation.
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 +      It integrates agricultural market projections from other institutions as OECD, FAPRI, FAO and DG-AGRI.
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 +      Unique for CAPRI is the regional resolution below the national level for EU27 at the level of
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 +      NUTS 2 regions and farm types inside NUTS 2 region, and the Bayesian methodology applied.</P>
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 +      <P>The <A HREF="supply.htm">supply</A> and <A HREF="market.htm">market</A> module
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 +      are calibrated to results of the reference run.</P>
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 +      <P>In opposite to many other reference run approaches, CAPRI employs a Bayesian estimation
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 +      framework to define a mutually consistent set of projection values for activity levels,
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 +      yields, production, feed and processing demand, human consumption, trade etc. Basically,
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 +      all major equations from the supply and market modules are defined as in an optimization
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 +      framework which maximizes the joint posterior density for given a priori distribution
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 +      of the different elements. The a priori distribution is whereever possible derived to from exogenous forecasts or expert information.</P>
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 +      </TD>
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 +      <TD><P><a href="images\refrun.gif"><img style="text-decoration: none;border: none;color: white" src="images\refrun.gif" width="500px"/></a></P>
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 +      </TD>
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 +      </TR>
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 +      </TABLE>
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 +      <H3>Methodology</H3>
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 +      <TABLE padding="10 px"><TR>
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 +      <TD><P><a href="images\support.jpg"><img style="text-decoration: none;border: none;color: white;padding:20px;margin:20px;" src="images\support.jpg" width="500px"/></a></P>
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 +      </TD>
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 +      <TD>
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 +      <P>The a priori distributions are derived from two different sources. For all elements,
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 +      long term trends are projected. Using "no change" as the zero hypothesis, a weighted average
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 +      between the base year value and the trend estimate is calculated, using R squared
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 +      as weight for the trend estimate. The
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 +      resulting estimates along with the estimation error of the trend deliver a priori distributions
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 +      for all items in the estimation framework.</P>
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 +      <P>In a first step, the estimation is solved for these trend support, indepedently for each country. Afterwards, results are aggregated to
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 +      EU. The projections of other instutions are then added, and replace where available the supports based on trends.
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 +      If the projections are only reporting values for the EU and not for individual countries,
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 +      the country results from the first steps are used to distributed the EU estimate. The standard errors for the there projections,
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 +      especially for those provided by DG-AGRI, is set rather narrow, ensuring that the values are recovered as long as they do not violate
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 +      the consistency restrictions.</P>
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 +     <P>The estimation is then repeated in a second step based on the updated supports. The country results are then taken is given, and broken
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 +     down in a similar framework to NUTS 2 level, and from there to farm type groups.</P>
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 +      </TD>
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 +      </TR>
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 +      </TABLE>
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 +     <H3>Quality control</H3>
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 +     <P>Due to the NUTS 2 resolution with its 280 regions, and the high number of activities, outputs and inputs covered by the CAPRI modelling
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 +     system, the references comprises several Mio numbers. Therefore, aggregates over activities (single cereals aggregated to all cereals)
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 +     and products, and over countries to EU15, EU10 etc. are defined and reported in tables accessible via the Graphical user interface.
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 +     Those tables compare systematically the different inputs (trend estimate, policy shift, estimation results from the different steps).</P>
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 +     <P>Nevertheless, checking results for plausibility remains a challenge. An interested comparison of the methdology between the reference
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 +     run exercise for the OECD/FAO AGLINK-COSIMO model with an estimated input of 20 person months and the CAPRI reference run
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 +     with an estimated inputs of about 2 person months is reported by <A HREF=http://purl.umn.edu/44120>Adenauer 2008</A>.</P>
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 +<H3>More information</H3>
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 +<P class="pubparagraph"><span class="pubAuthor">Witzke H.P. and Adenaeuer M.</span>:<BR>
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 +<I><a HREF="..\docs\capri_baseline.pdf" class="intext">Capri Baseline (pdf, 13 slides)</a></I></p>
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 +<font size=1>Last Updated:Tuesday, October 28, 2008
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 +</font>
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