# FAQs

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<summary>Where does the data for this ratio come from?</summary>

The tool pulls the official CAPE10 series from Multpl, which is based on the research of Yale Professor Robert Shiller.

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<summary>Why is the "Historical Mean" set to 17.0?</summary>

The long-term average of the Shiller PE since 1881 is approximately 17.0. Some investors prefer to use a higher mean (e.g., 19-20) for the post-WWII era.

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<summary>Does a high Shiller PE mean the market will crash immediately?</summary>

No. Valuations are not timing tools; markets can stay overvalued for years. It is a measure of long-term risk and future return expectations.

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<summary>What is the difference between Monthly and Yearly resolution?</summary>

Monthly provides more tactical data points, while Yearly is better for high-level secular trend analysis and historical backtesting.

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<summary>How should I interpret the "Deviation" stat in the dashboard?</summary>

It shows how far the current ratio is from the Historical Mean. A +50% deviation suggests the market is significantly stretched relative to its historical norm.

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