Relative Strength (IBD Style)

This script is meant to give you a Relative Strength indication of the stock. The goal is to use a similar calculation as used by IBD.
It calculates the performance of the current stock for the last year (most recent quarter is weighted double) and compares it to the performance of a reference index or ticker (default is "SPY").

IBD would give you a value between 0 and 100 because this value is the percentile within all stocks. This is not possible with Pine Script at the moment.
So here you get a Relative Strength value that is >0 if the stock is stronger than the index and <0 if it is weaker than the index.

You can still compare the Relative Strength values between stocks (bigger is better) but you won't know which percentile it is right off the bat.

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Fix typo and update chart.

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Update chart.

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Update chart.

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Improve performance value display.

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Streamline performance calculation.

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Update chart.

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Fixed a bug where the display would jump around during open market when you opened the reference ticker.

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Update chart.

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Fix chart flickering when viewing the reference.

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Fix broken graph.

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Fix broken graph. (Followup)

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Go back to quarterly calculation instead of monthly.