7-5-8

Graphing Paired-Variable Statistical Data

Cubic Regression

Model Formula: y = a·x3 + b·x2 + c·x + d

a : cubic regression coefficient

b : quadratic regression coefficient

c : linear regression coefficient

d : regression constant term (y-intercept)

r2 : coefficient of determination

MSe : mean square error

1

 

n

 

• MSe =

 

 

Σi=1

(yi – (a·xi3+ b·xi2+ c·xi +d ))2

n –

4

Quartic Regression

Model Formula: y = a·x4 + b·x3 + c·x2 + d·x + e

a : quartic regression coefficient

b : cubic regression coefficient

c : quadratic regression coefficient

d : linear regression coefficient

e : regression constant term (y-intercept)

r2 : coefficient of determination

MSe : mean square error

1

 

n

 

• MSe =

 

 

Σi=1

(yi – (a·xi4+ b·xi3 + c·xi2 + d·xi + e))2

n –

5

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