## Predictive Density Aggregation: A Model for Global GDP Growth

_IMF Working Papers, May 29, 2020_

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## Bibliographic details
- Authors: Francesca Caselli, Francesco Grigoli, Romain Lafarguette, Changchun Wang
- Published: May 29, 2020
- Series: IMF Working Papers
- DOI: https://doi.org/10.5089/9781513545653.001

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### Methodological approach
- Proposes a bottom-up probabilistic model to obtain the predictive density of global GDP growth.
- Estimates and combines single countries’ predictive GDP growth densities while taking into account cross-country interdependencies.
- Each economy’s predictive density depends on a set of observable country-specific factors.
- Uses sampling techniques to aggregate individual countries’ densities into a world aggregate while preserving the non-i.i.d. nature of the global GDP growth distribution.

### Modeling contemporaneous interdependencies
- Models non-parametrically the contemporaneous interdependencies across the United States, the euro area, and China via a conditional kernel density estimation of a joint distribution.
- Characterizes potential amplification effects stemming from other large economies in each region using kernel density estimations.
- Models the reaction of all other economies with parametric assumptions.

### Estimation and aggregation
- Combines non-parametric kernel density estimations for key large economies with parametric assumptions for other economies.
- Aggregation is performed via sampling techniques to preserve cross-country dependence and the non-i.i.d. global distribution.

### Evaluation and performance
- Out-of-sample metrics confirm the accuracy of the approach.

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_Source: https://www.imf.org/en/publications/wp/issues/2020/05/29/predictive-density-aggregation-a-model-for-global-gdp-growth-49441_