Psychology & Behavior
Inside View vs Outside View
內外部視角切換 · Source: Daniel Kahneman / Amos Tversky
Planning and forecasting — especially when you're overly optimistic about your own project, goals, or capabilities
Core Concept
"Inside view" is your perspective on your specific situation, usually full of optimism and detail. "Outside view" asks statistically: how do things like this typically go? The most effective approach: start with the outside view base rate, then make limited adjustments for your specifics.
✓ When to use this
When estimating project timelines/costs, predicting new venture success, or evaluating your "this time is different" reasoning. When you catch yourself saying "but our situation is special," that is the signal to switch.
✗ When not to use this
Genuinely unprecedented situations (no comparable outside reference) can only use the inside view. Decisions with solid historical data do not need to switch — use the base rate directly.
Questions you will be asked
Using this framework, you will work through —
- 1.What is your plan or decision?
- 2.Inside view: What are your expected timelines, costs, and success rate?
- 3.Outside view: How do similar plans typically turn out?
- …and 3 more
Worked example
Expand to see what a filled-in run looks like
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Worked example
Expand to see what a filled-in run looks like
Situation
預估自己花 6 個月、$300k 預算把 SaaS MVP 做到 $10k MRR。
1. What is your plan or decision?
6 個月內把產品做到 $10k MRR、$300k 預算內。
2. Inside view: What are your expected timelines, costs, and success rate?
我覺得 6 個月夠——核心功能 3 個月、推廣 3 個月。預算估 $250k，留 $50k buffer。成功率心裡覺得 60%。
3. Outside view: How do similar plans typically turn out?
YC 的數據：種子期 SaaS 平均 18 個月才到 $10k MRR；50% 失敗、25% 走到 $10k 但花更久、25% 走超過。第一次創業者多 30% 時間。
4. How large is the gap between your forecast and the outside base rate? What specifically justifies expecting to do better than average?
差距很大——我估 6 個月，外部基準是 18 個月。我憑什麼快 3 倍？
5. What advice would a complete outsider — knowing nothing about you personally — give when seeing your plan?
1) 我有產品市場匹配的訊號（10 個朋友願付）— 微弱優勢；2) 我有自己的工程能力，不用外包— 中度優勢；3) 我沒有銷售經驗— 劣勢。整體不足以快 3 倍，最多快 30%。
6. Having combined both views, how has your assessment of this plan changed?
局外人會說：你預算夠 9 個月不是 6 個月，把目標先設成 3 個月做到 $2k MRR、再決定要不要繼續。
Use it inside ChatGPT / Claude
Paste the prompt below and the AI will walk you through this framework, one question at a time.
你現在是引導使用者切換「內外部視角」的教練（Kahneman / Tversky）。 人們估計時間成本時習慣只看自己的具體情況（內部視角），卻忽視類似計畫的歷史結果（外部視角）。 依序問： 1) 你的計畫或決策是什麼？ 2) 內部視角：你預期的時間、成本、成功率？ 3) 外部視角：同類型的計畫，一般結果是什麼？（要他去查實際資料） 4) 你的預測和外部基準差距多大？你憑什麼比平均好？ 5) 一個完全不認識你的局外人會給什麼建議？ 6) 結合內外部後，修正後的預測是什麼？ 當使用者拒絕找外部資料、只用「我感覺」回答時，要求他先查再回。 互動規則： 1. 一次只問一題，等使用者回答後再進入下一題。 2. 使用者答完所有題目前，不要做總結或下結論。 3. 若答案太抽象、太籠統，請追問一次具體例子或數字後再繼續。 4. 全部答完後，輸出三段：(a) 摘要使用者的關鍵判斷；(b) 你看到的盲點或張力；(c) 一個具體下一步行動建議。 5. 不要替使用者做決定，只把判斷攤開讓他自己決定。
Related Frameworks
Psychology & Behavior
Base Rate Forecasting
Decisions requiring outcome forecasts — from startup success rates to investment returns, start by asking "how does this type of thing typically go"
Psychology & Behavior
Cognitive Bias Checklist
Pre-flight check before any important decision — scan for five high-frequency biases before you commit
FAQ
How is inside/outside view different from base rate forecasting?
Base rate forecasting is the more focused method — find a reference class and use its historical odds. Inside/outside view is the broader mindset shift: look from the outside statistics first, then adjust slightly with inside details. Base rate forecasting is essentially the core execution tool of the outside view.
Doesn't my specific situation matter, then?
It matters — but the order is what counts. Build the baseline from the outside view first (how this kind of thing usually goes), then make a limited adjustment for your specifics — rather than starting from inside optimism and grudgingly bolting on reality afterward. The common error isn't ignoring details; it's skipping the outside view step.
How do I pick the right outside reference class?
Choose a class that's structurally similar, not superficially similar — to assess your SaaS, the reference is "survival rates of solo startups at the same stage," not "the tech industry overall." More samples are better; if you feel you're an exception to the base rate, you need concrete evidence, not just a feeling of "I'm different."
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