StockFetcher Forums · General Discussion · RSI discrepancies<< 1 2 >>Post Follow-up
Fat Dragon
8 posts
msg #113170
Ignore Fat Dragon
5/7/2013 9:57:14 AM

HI:
I am using SF to sort RSI's and the values I get on the filter results do not correspond to values that show up on other peoples charts. Sometimes by a lot. I mean 20 or 30 points. I have tried using the straight RSI; smoothed RSI; and various versions of ERSI. none of them give me agreements. Often chart programs do not even agree with each other.
I know the more data points that are used the more accurate the value becomes and some people use 250 points but I would think over 50 or 100 data points the values should be closing in on each other. Does anyone have an ideas on how to close the gap in results?

Thanks,
Fat Dragon

stockfetcher
973 posts
msg #113171
5/7/2013 10:02:11 AM

Hi,

Thank you for the feedback. When you have a chance, please provide a few example charts from the other site(s). Also, make sure you're not comparing an intraday rsi period with our daily rsi values.

Feel free to email to support@stockfetcher.com

Thanks,
StockFetcher.com Support


Fat Dragon
8 posts
msg #113172
Ignore Fat Dragon
5/7/2013 10:10:47 AM

Thanks for the quick response. Look at KRG. On SF daily RSI(4) is 49.56. On FreeStockCharts.com Daily RSI(4) is 26.09. I don't get it.

Fat Dragon

stockfetcher
973 posts
msg #113175
5/7/2013 10:33:13 AM

Unfortunately, we have no method of verifying how the measure is computed on other sites, as well as what data is used as input.

Using the most recent completed market date, StockFetcher's RSI matches other popular charting services such as StockCharts, Yahoo Finance and Google Finance.

On StockFetcher when computing recursive measures, such as the RSI, at least 2 years of historical data is used to seed the measure.

StockFetcher Support



Fat Dragon
8 posts
msg #113176
Ignore Fat Dragon
5/7/2013 11:14:48 AM

Hi:
I looked at Yahoo Finance and they calculated it at 26.09. That is the same as Google Finance and FreeStockCharts.com. Stockcharts.com calculates it as about 39.73 which is closer the the49.56 which I am getting from SF.

Thanks for checking it out,
Fat Dragon



stockfetcher
973 posts
msg #113180
5/7/2013 11:27:09 AM

As indicated in our prior response, the values we were using to compare were based on yesterday's (May 6, 2013) close. Each of the services mentioned (with the exception of FreeStockCharts.com) match (within acceptable error) StockFetcher's value.

Because we have no method to validate the current intraday values on each site, as well as how each service computes the measure when using intraday data, it is not possible to compare partial-day values.

Please advise if you do not see matching values based on EOD data with each service.

StockFetcher Support


cflinn622
3 posts
msg #143291
Ignore cflinn622
4/22/2018 11:45:41 AM

I've noticed that the RSI calculation is often wildly off compared to other sites, to the point I not longer trust SF to produce accurate results for RSI.

Here's one example for TRMB for 4/18/2018

Using StockFetcher: RSI 7 = 73.4, RSI 21 = 51.5

Using FreeStockCharts and my own spreadsheet: RSI 7 = 94.1 and RSI 21 = 49.4

The 21-day is close-ish, while the 7 day is off by 20+% - either way, my offline spreadsheet produces FreeStockCharts number with 100% accuracy.

It isn't occasionally wrong, it's always inaccurate, sometimes just a little, but often by quite a lot as my example shows.



stockfetcher
973 posts
msg #143292
4/22/2018 1:13:43 PM

If possible, can you provide more details concerning the amount of history you are using to seed your RSI calculation? StockFetcher uses approximately 2 years of historical data.

Thanks!
StockFetcher Support


cflinn622
3 posts
msg #143293
Ignore cflinn622
4/22/2018 2:24:37 PM

I'm not sure what you mean by "seed".

The calculation RSI(days) uses data from the prior ## days. So the only interpretation of 'seed' I can think of is the day parameter. I typically use 7 and 21 - it doesn't matter how many years of history occurs prior to that.

http://stockcharts.com/school/doku.php?id=chart_school:technical_indicators:relative_strength_index_rsi#calculation

stockfetcher
973 posts
msg #143294
4/22/2018 3:08:33 PM

The RSI is a recursive calculation. With recursive measures, the starting point will impact the final values. Using less or different historical values to "seed" a recursive measure will introduce an error factor between implementations.

Specifically, the RSI on StockFetcher uses Wilder's Smoothing Average when generating the smoothed upward and downward price values. The Wilder's Smoothing Average, similar to an EMA, is a recursive calculation requiring the prior value to calculate the current value.

Additionally, we did verify that StockFetcher's RSI value for TRMB appears to match both StockCharts and Yahoo Finance:

StockFetcher


StockCharts.com


Yahoo! Finance









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

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