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Re: trendline fit
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From: |
Jamie O'Keefe |
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Subject: |
Re: trendline fit |
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Date: |
Thu, 06 May 1999 15:16:15 PDT |
The Least Squares method for y = ax + b is:
a = Sxy / Sxx and b = avg of y - a * avg of x
where:
Sxy = (Sum(xi * yi) - (n * avg of x * avg of y))
Sxx = (Sum(xi^2) - n * (avg of x) ^ 2)
xi is the i th instance of the x variable
yi is the i th instance of the y variable
n is the number of data points
Rules of sample sizes apply. You should be able to find these equations
(and more) in most any Econometrics textbook.
Jamie
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