StockFetcher Forums · General Discussion · RSI discrepancies<< 1 2 >>Post Follow-up
4 posts
msg #143296
Ignore cflinn622
4/22/2018 5:57:59 PM

Ok, I see what's going on now. There is:

"Straight" RSI - what the 'RSI' on FreeStockCharts uses, no smoothing
"Wilder's" RSI - includes a smoothing factor, but this seems to be the usual convention/common calculation and is simply referred to as RSI in most cases (i.e. the number returned on SF and the other sites referenced)
Not to be confused with "Smoothed RSI" on SF, which appears to add an additional smoothing factor

Anyway, I can verify that FreeStockCharts has a "Wilder's RSI" indicator that matches the "RSI" on other sites. I was using the "straight" RSI indicator for charting before on FSC, hence the discrepancy. The good news is that the Wilder's calculation appears to have better predictability.

Thank you for the prompt response to help me figure this out!

4 posts
msg #143385
Ignore Tracks
4/28/2018 9:15:02 PM

There are actually a few flavors to how you can compute RSI.

To calculate RSI you need:
- the average of your up days in the given period(let's call this value UP)
- the average of your down days (DOWN)
- Divide UP by Down to give a value we will call RS

RSI = 100 - (100 / (1 + RS))

The variation you are seeing mostly depends on how that average is calculated at the start. Wilder's uses a variation of an EMA, while you can also use a simple moving average, RMA or HMA to calculate. Unless someone specifies that it's Wilder's RSI, or Simple RSI, etc, you can't really compare them across sites.

StockFetcher Forums · General Discussion · RSI discrepancies<< 1 2 >>Post Follow-up

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