📖Warren Buffett

Approximately Right

🌿 Intermediate★★★★☆

A rough estimate of true value beats a precise calculation based on flawed assumptions.

💬

It is better to be approximately right than precisely wrong.

— 1989 Berkshire Hathaway Letter to Shareholders，1989

🏠 Everyday Analogy

Just as a traditional Chinese medicine practitioner can accurately diagnose an illness by feeling the pulse—without needing millimeter-precise CT scans—investment valuation follows a similar principle. Rather than relying on complex formulas to produce seemingly precise figures, it is more effective to use common sense to gauge what a company is approximately worth.

📖 Core Interpretation

Valuation is not an exact science. The pursuit of precise valuation models often creates a false sense of certainty.
💎 Key Insight：Finance obsesses over decimal-point precision in models built on uncertain assumptions. Buffett prefers a rough sense of whether something is cheap or expensive. If you need a spreadsheet to justify a stock purchase, the opportunity probably isn't compelling enough. The best investments are obvious at first glance.

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❓ Why It Matters

Buffett doesn't use complex DCF models: "If a company requires complicated calculations to prove it's cheap, it probably isn't cheap enough."

🎯 How to Practice

Practical Approach: Use conservative assumptions, maintain a sufficient margin of safety, and focus on key variables rather than precise figures.

🎙️ Master's Voice

It is better to be approximately right than precisely wrong.
Buffett distrusts elaborate financial models. A DCF with 50 inputs gives false precision. He prefers rough estimates: "This business is worth somewhere between $80 and $120 per share." A range based on sound logic beats false precision based on questionable assumptions.

⚔️ Practical Guide

✅ Decision Checklist

  • Am I seeking false precision in my valuation?
  • Are my core assumptions sound?
  • Can I express my valuation as a range?
  • Am I overconfident in my precise estimates?

📋 Action Steps

  1. Express valuations as ranges, not precise numbers
  2. Focus on getting key assumptions right
  3. Use simple models over complex ones
  4. Acknowledge uncertainty in your estimates

🚨 Warning Signs

  • Precise targets without acknowledging uncertainty
  • Complex models with dubious inputs
  • Overconfidence in valuation accuracy
  • False precision masking weak analysis

⚠️ Common Pitfalls

✕Valuation requires precision down to the decimal point — it is better to be vaguely right than precisely wrong.
✕Not using complex models is unprofessional - simple valuations make it easier to identify key assumptions.

📚 Case Studies

1
Warren Buffett's Valuation Method (1989)
Never use complex spreadsheets.
✨ Outcome：Using Simple Calculations to Determine if Something is Significantly Undervalued
2
LTCM's Precision Models (1998)
Using Complex Mathematical Models to Precisely Calculate Risk
✨ Outcome：The model failed to account for extreme scenarios and ultimately collapsed.

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