6-3-7

Calculating and Graphing Paired-Variable Statistical Data

kQuadratic/Cubic/Quartic Regression Graph

A quadratic/cubic/quartic regression graph represents connection of the data points of a scatter diagram. It uses the method of least squares to draw a curve that passes close to as many data points as possible. The formula that represents this is quadratic/cubic/quartic regression.

Ex. Quadratic regression

1(CALC)4(X^2)

6(DRAW)

Quadratic regression

Model formula ..... y = ax2 + bx + c

a............. regression second coefficient

b............. regression first coefficient

c............. regression constant term (y-intercept)

r2 ............

coefficient of determination

MSe ........

mean square error

Cubic regression

Model formula ..... y = ax3 + bx2 + cx + d

a............. regression third coefficient

b............. regression second coefficient

c............. regression first coefficient

d............. regression constant term (y-intercept)

r2 ............

coefficient of determination

MSe ........

mean square error

Quartic regression

Model formula ..... y = ax4 + bx3 + cx2 + dx + e

a............. regression fourth coefficient

b............. regression third coefficient

c............. regression second coefficient

d............. regression first coefficient

e............. regression constant term (y-intercept)

r2 ............

coefficient of determination

MSe ........

mean square error

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