Rough Estimation (Mao Gu Gu)
Better a rough correctness than precise error
📌 Concept Explanation
Rough Estimation = No need for precise calculator calculations; just roughly judge whether a company is obviously cheap—if you can figure it out in 5 minutes, it’s cheap enough.
You want to know how much heavier Yao Ming is than you—no need to put him on a scale; just standing there, anyone can see he’s heavier. Duan’s “rough estimation” means exactly this—if a company is so cheap that “you can tell at a glance,” that’s truly cheap; if you need to calculate on a calculator for half a day to find it’s only slightly cheap, it’s not cheap enough.
💡 Core Understanding
1. Valuation is fundamentally a rough estimation thing—if you need a calculator to calculate it’s cheap, it’s not cheap enough.
Yao Ming stands there and anyone can see he’s heavier than you—would you really need a scale? True cheapness is “obvious at a glance,” not a tiny discount calculated precisely.
2. Better a rough correctness than precise error.
Precise calculation gives a false sense of security—the more precise your calculated number, the more assumptions you’ve made about the future, and these assumptions themselves are uncertain.
3. The focus of rough estimation is on qualitative analysis, not quantitative calculation.
Rough estimation doesn’t mean no analysis—it means the focus of analysis is on “is the company good?” rather than “precisely calculating how much money.”
4. Rough estimation of course considers growth—discounting is the result of considering growth.
Rough estimation isn’t just looking at current profits; it’s a simplified version of discounted future cash flows—incorporating future growth without needing precise calculation.
💬 Original Quotes
“I think valuation is fundamentally a rough estimation thing—if you need a calculator to figure out it’s cheap, it’s not cheap enough.” (Source: Investment Logic Chapter, Section 5.1, 2010-04-25)
“Yao Ming stands there and anyone can see he’s heavier than me—do you really need a scale to know?” (Source: Investment Logic Chapter, Section 5.2, 2019-03-20)
“What rough estimation means is I actually don’t know what discount to apply. Anyway, it definitely feels obviously cheap—that kind of price where you won’t lose sleep over it.” (Source: Investment Logic Chapter, Section 5.2, 2011-01-19)
“‘Better a rough correctness than precise error’…I think this is what I mean by rough estimation.” (Source: Investment Logic Chapter, Section 5.2, 2018-05-28)
“Rough valuation is mainly used to judge downside potential; qualitative analysis is the true source of profits—and this might be the hardest thing in value investing.” (Source: Investment Logic Chapter, Section 5.1, 2010-04-25)
⚠️ Common Misconceptions
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❌ “Valuation needs precise calculation—only reliable if using DCF formulas to get exact numbers” — “Munger said he never saw Buffett use a calculator to value a company; I don’t seem to have ever really used a calculator for valuation either.” Precise calculation gives a false sense of security; true valuation is qualitative judgment.
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❌ “Rough estimation means just guessing, no serious analysis needed” — “Qualitative analysis is the true source of profits—and this might be the hardest thing in value investing.” Rough estimation doesn’t mean no analysis; it means focusing on qualitative analysis (is the company good?) rather than quantitative (precisely calculating how much).
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❌ “Rough estimation doesn’t consider growth, only looks at current profits” — “Rough estimation of course considers growth. Discounting is the result of considering growth.” Rough estimation is a simplified version of discounted future cash flows, not ignoring the future.
🔗 Related Nodes
Upstream Concepts (prerequisites for understanding this concept): Discounted Future Cash Flows · Circle of Competence · Margin of Safety
Downstream Concepts (conclusions derived from this): Buy Logic · Sell Logic
Related Company Cases NetEase (bought via rough estimation, rose 160x) · Vanke (sold via rough estimation) · Apple
Related Figures Duan Yongping · Buffett · Munger
毛估估
宁要模糊的正确，也不要精确的错误
📌 概念解析
毛估估 = 不用计算器精确计算，只需大致判断公司是否明显便宜，5分钟能算明白的才够便宜。
你想知道姚明比你重多少，不需要拿磅秤量——他往那里一站，谁都能看出来他比你重。 段永平的毛估估就是这个意思——如果一家公司便宜到”一眼就能看出来”，那才是真正的便宜；如果需要按半天计算器才能算出来一点点便宜，那就不够便宜。
💡 核心理解
1. 估值就是个毛估估的东西，用到计算器才能算出来的便宜就不够便宜。
姚明往那里一站，谁都能看出来他比你重，难道还要用磅秤？真正的便宜是”一眼就能看出来”的便宜，而不是精确计算出来的一点点折扣。
2. 宁要模糊的正确，也不要精确的错误。
精确计算给人一种虚假的安全感——你算出来的数字越精确，往往说明你对未来的假设越多，而这些假设本身就是不确定的。
3. 毛估估的重点在定性分析，不在定量计算。
毛估估不是不分析，而是分析的重点在”公司好不好”，而不是”精确算出多少钱”。
4. 毛估估当然要考虑成长性，折现就是考虑成长性以后的结果。
毛估估不是只看当前利润，而是未来现金流折现的简化版——把未来的成长性也纳入考虑，只是不需要精确计算。
💬 原文金句
“我认为估值就是个毛估估的东西，如果要用到计算器才能算出来的便宜就不够便宜了。“（来源：投资逻辑篇·第五章第1节，2010-04-25）
“姚明往那里一站，谁都能看出来他比我重，难道还要用磅秤后才知道？“（来源：投资逻辑篇·第五章第2节，2019-03-20）
“毛估估的意思就是其实我也不知道该打几折。反正肯定觉得很明显便宜就是了，就是那种不会睡不着觉的价錢。“（来源：投资逻辑篇·第五章第2节，2011-01-19）
“‘宁要模糊的正确，也不要精确的错误’……我觉得这就是我说的毛估估的意思。“（来源：投资逻辑篇·第五章第2节，2018-05-28）
“大致的估值主要用于判断下行的空间，定性的分析才是真正利润的来源，这也可能是价值投资里最难的东西。“（来源：投资逻辑篇·第五章第1节，2010-04-25）
⚠️ 常见误区
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❌ “估值需要精确计算，用DCF公式算出精确数字才可靠” — “芒格说他从来没见巴菲特按着计算器去估值一家企业，我好像也没真正用过计算器做估值”。精确计算给人一种虚假的安全感，真正的估值是定性判断。
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❌ “毛估估就是随便猜，不需要认真分析” — “定性的分析才是真正利润的来源，这也可能是价值投资里最难的东西”。毛估估不是不分析，而是分析的重点在定性（公司好不好）而不是定量（精确算出多少钱）。
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❌ “毛估估不考虑成长性，只看当前利润” — “毛估估当然要考虑成长性。折现就是考虑成长性以后的结果”。毛估估是未来现金流折现的简化版，不是不考虑未来。
🔗 关联节点
上游概念（理解这个概念的前提）： 未来现金流折现 · 能力圈 · 安全边际