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Substrate/Data/US-Inflation/US-Inflation-CPI-1947-2025.md
Daniel Miessler c1d6b0b9f8 Add U.S. Inflation dataset with comprehensive CPI data (1947-2025) 
Created new US-Inflation data directory with:
- 945 monthly CPI-U observations from FRED/BLS (Jan 1947 - Aug 2025)
- Comprehensive metadata documentation with methodology
- README with source research and justification
- UPDATES.md change log and update procedures
- RESOURCES.md with data sources and API access
- Structure mirrors existing COVID wastewater dataset

Data source: FRED Series CPIAUCSL (CPI for All Urban Consumers, Seasonally Adjusted)
Update frequency: Monthly (mid-month BLS releases)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>
2025-10-07 17:48:25 -07:00

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U.S. Consumer Price Index (CPI) - Inflation Data

Metadata

Data Source: Federal Reserve Economic Data (FRED) / U.S. Bureau of Labor Statistics (BLS) Primary URL: https://fred.stlouisfed.org/series/CPIAUCSL Direct CSV: https://fred.stlouisfed.org/graph/fredgraph.csv?id=CPIAUCSL&cosd=1947-01-01 BLS Series: CPIAUCSL (Consumer Price Index for All Urban Consumers: All Items in U.S. City Average) Update Frequency: Monthly (released mid-month following data month at 8:30 AM ET) Last Updated: 2025-10-07 Coverage: United States, January 1947 - Present License: Public domain (U.S. government data)

Data Description

Primary Metrics

Consumer Price Index (CPI-U): Measures changes in the price level of a weighted average market basket of consumer goods and services purchased by households

  • Unit: Index value (1982-1984 = 100 baseline)
  • Population Coverage: All Urban Consumers (approximately 93% of U.S. population)
  • Seasonally Adjusted: Yes
  • Base Period: 1982-1984 = 100

Data Format

The FRED dataset provides:

  • observation_date: Month identifier (YYYY-MM-DD format, first day of month)
  • CPIAUCSL: CPI-U index value (seasonally adjusted)

Calculation Methodology

  • Index Calculation: Laspeyres price index formula
  • Basket Composition: ~80,000 items across 8 major categories:
    • Food and beverages
    • Housing
    • Apparel
    • Transportation
    • Medical care
    • Recreation
    • Education and communication
    • Other goods and services
  • Weight Updates: Basket weights updated every 2 years based on Consumer Expenditure Survey
  • Geographic Coverage: 75 urban areas across the United States

Key Insights from Data

Current Status (August 2025)

  • Latest Reading: 323.364 (August 2025)
  • Year-over-Year Inflation: Approximately 2.5% (based on 12-month change)
  • Trend: Moderating from 2022-2023 peaks, stabilizing near Federal Reserve target

Historical Context

  • Post-WWII Low: 21.480 (January 1947)
  • 2022-2023 Peak: 317.603 (December 2024)
  • Total Increase: 1,404% from 1947 to 2025 (78-year period)
  • Average Annual Inflation: ~3.5% over full period

Major Inflation Episodes

  • 1970s Stagflation: Double-digit inflation (peak 14.8% in 1980)
  • Great Moderation (1990s-2000s): Stable ~2-3% annual inflation
  • Great Recession (2008-2009): Brief deflationary period
  • COVID-19 Response (2021-2023): Rapid inflation surge to 9.1% (June 2022)
  • Current Period (2024-2025): Gradual return to ~2% target

Inflation Rate Calculation

To calculate year-over-year inflation rate:

Inflation Rate = ((CPI_current - CPI_12months_ago) / CPI_12months_ago) × 100

Example (August 2025):

  • Current: 323.364
  • One year ago (Aug 2024): ~315.5
  • Inflation: ((323.364 - 315.5) / 315.5) × 100 ≈ 2.5%

Data Sources & Alternative Access

Primary Sources

  1. FRED (Federal Reserve Economic Data): https://fred.stlouisfed.org/series/CPIAUCSL
  2. BLS Official CPI Page: https://www.bls.gov/cpi/
  3. BLS Data Tools: https://data.bls.gov/timeseries/CPIAUCSL

Related CPI Series

  • CPILFESL: CPI for All Urban Consumers: All Items Less Food & Energy (Core CPI)
  • CPIAUCNS: CPI-U Not Seasonally Adjusted
  • CPIENGSL: CPI for Energy
  • CPIFABSL: CPI for Food and Beverages

API Access

Usage Notes

Data Quality

  • Reliability: Gold standard for U.S. inflation measurement
  • Frequency: Monthly updates (mid-month release)
  • Timeliness: Published ~2 weeks after month end
  • Revisions: Minimal - typically only seasonal adjustment factors revised
  • Completeness: 945 monthly observations (1947-2025)

Interpretation Guidelines

  1. Index vs. Rate: CPI is an index; inflation rate is the percentage change
  2. Compounding Effects: Small annual rates compound significantly over decades
  3. Purchasing Power: CPI of 100 in 1984 requires ~323 today for equivalent purchasing power
  4. Real vs. Nominal: Use CPI to adjust nominal dollars to real (inflation-adjusted) values
  5. Base Period: 1982-1984 average = 100 baseline

Limitations

  • Substitution Bias: Fixed basket doesn't capture consumer substitution behavior
  • Quality Changes: Difficult to adjust for product quality improvements
  • New Products: Slow to incorporate new goods and services
  • Geographic Variation: National average masks regional differences
  • Population Coverage: Excludes rural households (~7% of population)

Related Substrate Components

Claims Supported:

  • CPI as authoritative measure of inflation and purchasing power
  • Federal Reserve monetary policy effectiveness
  • Impact of fiscal/monetary policy on price levels

Problems Addressed:

  • Economic planning and policy-making requiring accurate inflation data
  • Wage and benefit adjustments (COLAs)
  • Real return calculations for investments

Solutions Enabled:

  • Inflation-adjusted economic analysis
  • Cost of living comparisons across time periods
  • Monetary policy decision-making

Data Processing Notes

The accompanying CSV file (CPI-US-Monthly-1947-2025.csv) contains:

  • FRED series CPIAUCSL (CPI-U seasonally adjusted)
  • Monthly observations from January 1947 through August 2025
  • Index values with 3 decimal place precision
  • ISO 8601 date format (YYYY-MM-DD)

Use Cases

This dataset supports:

  • Economic Research: Historical inflation analysis and forecasting
  • Policy Analysis: Federal Reserve and Treasury decision-making evaluation
  • Financial Planning: Real return calculations, retirement planning
  • Wage Negotiations: COLA adjustments based on CPI changes
  • Academic Research: Macroeconomic studies and modeling
  • Substrate Integration: Supporting Claims, Arguments, and economic Models with authoritative data

References

  1. BLS CPI Overview: https://www.bls.gov/cpi/overview.htm
  2. BLS CPI FAQ: https://www.bls.gov/cpi/questions-and-answers.htm
  3. FRED CPIAUCSL Series: https://fred.stlouisfed.org/series/CPIAUCSL
  4. BLS Handbook of Methods (Chapter 17 - CPI): https://www.bls.gov/opub/hom/cpi/
  5. Federal Reserve Inflation Targeting: https://www.federalreserve.gov/faqs/economy_14400.htm

Dataset Purpose: Provide authoritative, comprehensive U.S. inflation data to support economic analysis, policy evaluation, and real-value calculations within the Substrate knowledge system.

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