| Gravity covariates |
| --- |
| This folder contains unilateral and bilateral covariates used to train the model. |
| GDP data, which is stored in the `Data/GDP_data` folder. Demographic data, such as total population, and |
| birth and death rates, is given in the `Data/UN_WPP_data` folder. Conflict data is stored in the |
| `Data/UNCDP_data` folder, and refugee data is given in `Data/UNHCR_data`. |
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| ## Bilateral trade (`trade_flows`) |
| Total trade flow between origin and destination is taken from the [CEPII BACI dataset](https://www.cepii.fr/CEPII/en/bdd_modele/bdd_modele_item.asp?id=37), |
| which contains data from 1995–2023. We deflate to const. 2015 USD using the World Bank GDP deflator (provided in the |
| `GDP_data` folder) and fill missing values using the growth rates from UN Comtrade and IMF data, which are also provided |
| by CEPII. Remaining NaN values are backwards-filled using the last known value. Only the `Value (2015 USD)` variable is |
| complete for the period from 1990, since this is the only covariate we are using as a training input. |
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| ## Linguistic similarity (`lang`) |
| Linguistic similarity is taken from the USITC [Domestic and International Common Language Database (DICL)](https://www.usitc.gov/data/gravity/dicl.htm) |
| language database. We use the ``csl`` (common spoken language index). |
| As detailed in the description, data for 46 countries is missing: ``AFG, ALA, ANT, ARE, BHR, BIH, BLM, BMU, CCK, CXR, CYM, ERI, FLK, FRO, GGY, GRD, GRL, IOT, ISL, JEY, KNA, KWT, LBY, LIE, MAF, MDV, MSR, NFK, OMN, PCN, PRK, PSE, SDN, SHN, SMR, SOM, |
| SPM, SXM, SYR, TCA, TJK, TKL, VAT, VCT, VGB, VNM`` |
| In these cases, we use the average of linguistic proximity (``lpn``) and common native language (``cnl``) instead, as |
| recommended by the authors. For the remaining missing datapoint (BES islands), we use Curacao as a proxy. |
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| ## Religious similarity (`relig`) |
| This is calculated from the ['Correlates of War'](https://correlatesofwar.org/data-sets/world-religion-data/) database, |
| which gives the shares of religious adherence for each country. |
| Missing values are taken from the [CIA World Factbook](https://www.cia.gov/the-world-factbook/). |
| The religious similarity between two countries is then simply $\langle \alpha_i, \alpha_j \rangle$, |
| where $\alpha_i$ is the religious makeup of country $i$. The 'other' category is excluded (``othrgenpct``). |
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| ## EU membership (`eu`) |
| Information on EU membership is taken from the CEPII dataset. |
| Since EU membership structure has not changed since 2021 (Brexit), we can extrapolate those values forward. |
| EU membership is marked with a '1', non-membership is marked with a 0. |
| |
| ## Colonial ties (`col`) |
| Colonial ties are taken from the USITC DGD gravity database (``colony_of_destination_ever``). |
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| ## Geographic distance (`dist.nc`) |
| Distance is taken from the CEPII dataset (``distw_harmonic``). |
| This is the population-weighted distance between countries. |
| Though the covariates in CEPII is time-dependent, we take the time-averaged value to facilitate predictions on |
| new (future/past) data. Missing datapoints are the British Virgin Islands (VGB) and the Isle of Man (IMN). For the former, |
| we use the data for the U.S. Virgin Islands and set the distance (VGB-VIR) to 80 km. For the latter, we use the UK data and |
| set the distance (IMN-GBR) to 300 km. |
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