How can I regress a number series in Excel?
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jcollum
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Published on 2011-02-17T20:51:12Z
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2011/02/17
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excel
|regression
I'd like to use these data to derive an equation using Excel.
300 13
310 12.6
320 12.2
330 11.8
340 11.4
350 11
360 10.8
370 10.6
380 10.4
As x goes up, y goes down. Seems straightforward. But when I do a polynomial regression on these data, even though the trendline matches the data pretty well, the equation it generates doesn't work. The equation is 
When I plug in x values to that equation, the numbers go up! So something is pretty wrong here.
My steps:
- place both number series in excel
- select the second set (13, 12.6 ...)
- plot a line graph
- set the first set as the x axis labels
- select Series1 and add a polynomial (2) trendline, display equation, display R-squared
That produces the equation above, with an R^2 value of .9955. But when I use that equation, it doesn't produce those outputs for those inputs.
Clearly I'm doing something wrong.
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