每日钉一下（估值百分位，在哪些情况下可能会失效？）

Group 1 - The article discusses the importance of understanding investment strategies for index funds to achieve good returns [2] - A free course is offered to help investors learn index fund investment techniques, along with course notes and mind maps for efficient learning [2] Group 2 - The article highlights three situations where valuation percentiles may fail as a judgment indicator in investments [6] - Situation one involves significant earnings volatility, which can lead to ineffective price-to-earnings (P/E) ratios; in such cases, price-to-book (P/B) ratios can be referenced as an alternative [7][8] - Situation two pertains to indices with a short historical record, where low valuation percentiles may not indicate undervaluation due to insufficient historical data [10] - Situation three addresses changes in index rules, which can significantly alter valuation data; for example, the changes in the China Securities 100 index in June 2022 led to a shift in P/E ratios from around 10 to 13-14 [11][12]