业务方程式框架

将任何商业模式提炼为一个核心数学等式。等式输出通常为 ARR 或 Revenue，通过拆解输入变量，明确业务增长的具体路径。针对不同商业模式，有对应的核心等式模板：

1. B2B SaaS: ARR = New ARR + Expansion ARR + Reactivation ARR – Churned ARR – Contraction ARR
   • 适用于 Bottom-up（按席位/按使用量定价）或 Top-down（销售主导）。
2. B2C 订阅: ARR = (New subs + Retained subs + Reactivated subs) * Average monthly revenue per sub * 12
3. B2C 广告: Revenue = Active users * Impressions per user * CPM/CPC/CPA
4. Marketplaces (B2C/B2B): Revenue = Transactions * AOV * Take rate
5. DTC/E-commerce: Revenue = Transactions * AOV

每个高阶变量需继续向下拆解（如 New ARR = New seats * price per seat，New seats = Visitors * conversion rates），直到触及可执行的具体营销或产品动作。