Calculating the Y-Intercept

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The page below is a sample from the LabCE course Linear Regression Analysis. Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

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Calculating the Y-Intercept

To find the y-intercept, calculate and , the average of the x- and y-values respectively.

Then substitute these two values for x and y in the = b + a equation. Finally, solve for the unknown quantity a. Remember from the previous page that:

Therefore, the complete relationship between glucose concentration and absorbance for the data is y = 0+ 0.002x, or y = 0.002x, where y is the absorbance and x is the glucose concentration.