Does scattered polynomial trend line also provide coefficient of correlation?

[Zhenyu Hu]

Dear All,

I am using Google Chart API to draw a scattered polynomial trend line.

I know the chart provide the R square (coefficient of determination) which I am using, but I just wonder if it also provide the value of coefficient of correlation? 

I want to get this value to make cross reference.

PS: I didn't find it from the API document; if they don't support it, does anybody know if there is a JS plugin to calculate it.

Thanks a lot,

Kevin

[Sergey Grabkovsky]

The coefficient of correlation (or the r^2 value) should indeed be supported for all trendlines. You can enable it by setting the trendline option "showR2" to true.

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[Zhenyu Hu]

Hi Sergey,

Thanks for the feedback!

R2 is coefficient of determination which API indeed support it; however, coefficient of correlation (r) is a different one.

Below is the link to show the difference between the two

http://mathbits.com/MathBits/TISection/Statistics2/correlation.htm

Thanks,

Kevin

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[Sergey Grabkovsky]

Sorry, I didn't read carefully enough. We don't provide the value, nor do I think there's any reasonable way to calculate it. There's a stickied post on this forum where I asked what the ideal API is for getting trendline data out of the chart. We don't quite have a roadmap for this, but your opinion might help us determine the right solution.

[Zhenyu Hu]

Hi Sergey,

Thanks for the clarification!

Kevin