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 coeffi cient

b...............

regression fi rst coeffi cient

c...............

regression constant term (y-intercept)

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

coeffi cient of determination

MSe ........

mean square error

Cubic regression

 

 

Model formula.......

y = ax3 + bx2 + cx + d

a...............

regression third coeffi cient

b...............

regression second coeffi cient

c...............

regression fi rst coeffi cient

d...............

regression constant term (y-intercept)

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

coeffi cient of determination

MSe ........

mean square error

Quartic regression

 

Model formula.......

y = ax4 + bx3 + cx2 + dx + e

a...............

regression fourth coeffi cient

b...............

regression third coeffi cient

c...............

regression second coeffi cient

d...............

regression fi rst coeffi cient

e...............

regression constant term (y-intercept)

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

coeffi cient of determination

MSe ........

mean square error

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