# Source snapshots

These files freeze the exact URL inputs used by the original course examples. They were retrieved on 2026-07-16 and are transformed by `code/build_empirical_data.R`.

| Local file | Original URL / identifier | MD5 |
|---|---|---|
| `DEXJPUS_2020_2022.csv` | `https://fred.stlouisfed.org/graph/fredgraph.csv?id=DEXJPUS&cosd=2020-01-01&coed=2022-12-16` | `c2865c04ab321c79cfb9d861eeabffae` |
| `DEXTAUS_2020_2022.csv` | `https://fred.stlouisfed.org/graph/fredgraph.csv?id=DEXTAUS&cosd=2020-01-01&coed=2022-12-16` | `fede2d1ad0fd9b0119b988128709a9e0` |
| `d-msft8608.txt` | `https://faculty.chicagobooth.edu/-/media/faculty/ruey-s-tsay/teaching/fts3/d-msft8608.txt` | `84908669244b0d3bc345fa4645d43a1f` |
| `m-5clog-9008.txt` | `https://faculty.chicagobooth.edu/-/media/faculty/ruey-s-tsay/teaching/fts3/m-5clog-9008.txt` | `4145201eea412bc4c5df82f8dd74be6f` |
| `m-barra-9003.txt` | `https://faculty.chicagobooth.edu/-/media/faculty/ruey-s-tsay/teaching/fts3/m-barra-9003.txt` | `510485c308be0ce9e54a84b03a60d96a` |

The checksum values above are checked against the files before a release. A changed upstream response must be treated as a new data version, not silently substituted for the book snapshot.