# US-GDP Dataset Update Log

This file tracks all updates, revisions, and changes to the U.S. GDP dataset in Substrate.

---

## 2025-10-16 - Initial Dataset Creation

**Action**: Created US-GDP dataset with comprehensive research and documentation

**Data Added:**
- Real-GDP-Quarterly-1947-2025.csv (314 data points, Q1 1947 - Q2 2025)
- Real-GDP-Annual-1929-2024.csv (96 data points, 1929-2024)

**Source**: FRED (Federal Reserve Economic Data), sourcing from BEA
- Quarterly Real GDP: FRED Series GDPC1
- Annual Real GDP: FRED Series GDPCA

**Research Process:**
- 10 parallel research agents launched simultaneously
- 20 total queries (10 primary, 10 follow-ups)
- 3 research services used (Perplexity API, Claude WebSearch, Gemini)
- 95%+ confidence level in source selection

**Key Research Findings:**
- BEA identified as primary official U.S. government source
- FRED confirmed as most accessible distribution platform
- Real GDP preferred over nominal for economic analysis
- Quarterly data preferred for historical trend analysis
- Data quality: Three-stage quarterly revision + annual comprehensive update

**Coverage:**
- **Quarterly**: Q1 1947 to Q2 2025 (78+ years)
- **Annual**: 1929 to 2024 (96 years)
- **Extended historical**: 1790+ available via MeasuringWorth (not included in this dataset)

**Latest Data Points:**
- Quarterly: Q2 2025: $23,770.976 billion (chained 2017 dollars)
- Annual: 2024: $23,358.435 billion (chained 2017 dollars)

**Documentation Created:**
- README.md - Comprehensive dataset documentation with research methodology
- RESOURCES.md - Data sources, APIs, download methods, update procedures
- UPDATES.md - This file
- US-GDP-1929-2025.md - Detailed metadata (pending)

**Next Update Recommended**: After Q3 2025 third estimate release (expected late January 2026)

---

## Future Updates

New updates will be added above this line in reverse chronological order (newest first).

### Update Guidelines

**When to Update:**
1. After BEA releases third estimate for each quarter (most complete data)
2. After BEA's annual comprehensive update in September (historical revisions)
3. When methodology changes are announced by BEA

**Update Process:**
1. Download latest data from FRED
2. Verify data integrity (row counts, date ranges, latest values)
3. Cross-check with BEA news releases
4. Update CSV files with new data
5. Document changes in this file
6. Update README.md if methodology or coverage changes
7. Update main Data/UPDATES.md

**Data Verification:**
```bash
# Check quarterly file
wc -l Real-GDP-Quarterly-1947-2025.csv
head -3 Real-GDP-Quarterly-1947-2025.csv
tail -3 Real-GDP-Quarterly-1947-2025.csv

# Check annual file
wc -l Real-GDP-Annual-1929-2024.csv
head -3 Real-GDP-Annual-1929-2024.csv
tail -3 Real-GDP-Annual-1929-2024.csv
```

**BEA Release Schedule:**
- Advance Estimate: ~30 days after quarter end
- Second Estimate: ~60 days after quarter end
- Third Estimate: ~90 days after quarter end ← **Best time to update**
- Annual Comprehensive: September each year

---

**Maintained By**: Substrate Data Curation
**Update Frequency**: Quarterly (after third estimate) + Annual (after September revision)