| --- |
| pretty_name: Migration explorer database |
| language: |
| - en |
| tags: |
| - migration |
| - demography |
| - duckdb |
| viewer: false |
| --- |
| |
| # Migration explorer database |
|
|
| The database behind the **Migration explorer**, an interactive explorer for the UN migration flow estimates. For each |
| country, it holds the estimates together with all the data used as training targets or inputs, the data that were |
| considered and not used or excluded (with the reason), and where each value comes from. |
|
|
| > **Private, work in progress.** The new estimates (`source_id` `estimates`, `estimates_bilateral`) come from the |
| > published ensemble fine-tuned on the updated training data. They are preliminary and not a release. The estimates of |
| > Gaskin & Abel (Nature 2026) are included for comparison as `published_estimates` and `published_estimates_bilateral`. |
| |
| ## Contents |
| |
| `explorer.duckdb`, the database, which each pipeline run replaces. Alongside it, in `estimates/`, the estimates of |
| the fine-tuned ensemble as CSV files, in the format of the published estimates (also in the database): |
| |
| - `estimates/mig_unilateral.csv`: by country and year, net migration (`net`), immigration (`imm`), emigration (`emi`), |
| and the migrant stocks at the start of the year (`imm_pop`: foreign-born; `emi_pop`: born in the country, living |
| abroad), as the ensemble mean, with the standard deviation in `<column>_std` |
| - `estimates/mig_bilateral.csv`: by origin, destination and year, the flows by previous residence (`mig_prev`) and by |
| country of birth (`mig_brth`), and the bilateral stocks by country of birth at the start of the year (`stock_mean`), |
| each with its standard deviation (`mig_prev_std`, `mig_brth_std`, `stock_std`) |
|
|
| The database is built by `Explorer/build_db.py` in the |
| `Migration_flows_extended` repository, from the exports of its notebooks, the estimates, the UNPD candidate targets |
| and the provenance descriptions in `Explorer/sources.yaml`. The explorer (`Migration_explorer` repository) downloads it |
| at start and only displays it, without computing anything. |
|
|
| The table layout is defined in `Explorer/schema.sql` of the pipeline repository, which is the interface between the |
| two repositories. The `meta` table records the build: |
|
|
| | key | value | |
| |---|---| |
| | `schema_version` | version of the table layout (increased for changes that break the explorer) | |
| | `built_at` | time of the build | |
| | `pipeline_commit` | commit of `Migration_flows_extended` it was built from (`+dirty`: with uncommitted changes) | |
|
|
| ## Tables |
|
|
| | Table | Contents | |
| |---|---| |
| | `countries` | ISO 3166 alpha-3 code, name, alpha-2 code | |
| | `sources` | every source (`source_id`), with name, URL, description (markdown) and vintage | |
| | `country_series` | annual country series: net migration, immigration, emigration, and the migrant stocks `foreign_born` and `born_abroad` | |
| | `net_migration_consistency` | consistency of each national net migration series with the UN DESA stocks (the basis of its weight) | |
| | `provenance` | per country and quantity: what is used, what is excluded and why, dated decisions, caveats (markdown) | |
| | `flows` | bilateral flows by previous residence (`residence`) and by country of birth (`birth`): all flow data, the UNPD candidates, the estimates | |
| | `flow_source_weights` | the weights of the flow sources by source, reporter and direction | |
| | `stocks` | bilateral migrant stocks by country of birth: UN DESA revisions, corrected and start-of-year stocks, their changes between stock years (the targets), the estimates | |
| | `notes` | texts not tied to a country: source descriptions, flow weights, the stock methodology, the change history | |
| | `covariates` | country covariates (GDP, population, life expectancy, birth and death rates, conflict deaths, EU membership), with the source and kind of source of each value | |
| | `bilateral_covariates` | trade, refugees, distance, linguistic and religious similarity, colonial ties (non-zero values only) | |
| | `data_vintages` | the date of every download and of every input placed by hand | |
|
|
| All values are in persons unless the schema says otherwise. Years are calendar years. Stocks and the stock-based series |
| refer to the start of the year, and the UN DESA revisions to mid-year. |
|
|
| ### Status of a value |
|
|
| | `status` | meaning | |
| |---|---| |
| | `target` | used as a training target, with its `weight` | |
| | `reference` | shown for comparison, not a target (e.g. WPP where national data exist) | |
| | `not_used` | considered but not used, e.g. a usable candidate that was not adopted | |
| | `excluded` | rejected, with the reason in `reason` | |
| | `estimate` | model estimate, with `lower` and `upper` (mean ± 1 s.d. of the ensemble) | |
| | `input` | covariates: the value used by the pipeline | |
|
|
| ## Usage |
|
|
| Access needs a Hugging Face token with read access to this repository (`hf auth login`, or `HF_TOKEN`). |
|
|
| ```python |
| import duckdb |
| from huggingface_hub import hf_hub_download |
| |
| path = hf_hub_download("ThGaskin/Migration_explorer_db", "explorer.duckdb", repo_type="dataset") |
| con = duckdb.connect(path, read_only=True) |
| con.sql(""" |
| SELECT year, source_id, value, status, weight |
| FROM country_series |
| WHERE iso = 'DEU' AND quantity = 'net_migration' |
| ORDER BY year, source_id |
| """).df() |
| ``` |
|
|
| ## Sources |
|
|
| The data come from many providers: national statistical offices, UN DESA (WPP 2024, international migrant stocks), |
| the UNPD flow database, Eurostat, QuantMig, UNHCR, the World Bank, IMF, UCDP, CEPII, USITC and others. The `sources` |
| table lists each one with its URL and vintage, and their terms of use apply to the values taken from them. This |
| database is a working tool for the project and is not for redistribution. |
|
|
