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Data Transformations Reference

Quick reference guide for all available FRED data transformations.

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Transformation Codes

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Selection Guide

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By Data Type

Flow Variables (rates, prices):

• Use: pch, pc1, pca
• Example: Inflation, interest rates

Stock Variables (levels, balances):

• Use: chg, ch1
• Example: Employment, inventories

Financial Returns:

• Use: cch, log
• Example: Stock prices, exchange rates

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Common Mistakes

❌ Don’t:

• Transform already-transformed series
• Mix frequencies when comparing
• Ignore seasonal adjustment

✅ Do:

• Check original units
• Use consistent transformations
• Document your choices

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Next Steps