beautypg.com

Quadreg, Quadreg quadreg – Texas Instruments TI-73 EXPLORER User Manual

Page 150

background image

144

Chapter 7: Statistical Analyses

7307ENG.DOC CH 7, Statistical Analyses, English Julie Hewlett Revised: 07/29/98 12:07 PM Printed: 05/19/99

9:00 AM Page 144 of 22

5. View the line on the Graph

screen.

(

7

6. View the equation stored to

Y

2

, if desired.

&

QuadReg

QuadReg -

v

!

6

6

QuadReg

(quadratic regression) fits the second-degree

polynomial

y=ax

2

+bx+c

to the data. It displays values for

a

,

b

,

and

c

; when

DiagnosticOn

is set, it also displays a value for

r

2

(coefficient of determination). The

DiagnosticOn

command is in

the

CATALOG

(- |). You can execute the

QuadReg

command from the Graph screen, the Home screen, or the

Program editor.
For three data points, the equation is a polynomial fit; for four

or more, it is a polynomial regression. At least three data

points are required.
From the Home screen or the Program editor,

QuadReg

accepts

four optional arguments. Enter up to two list names, XList and

YList; a frequency list, freq; and an equation variable, Yn. freq

is the frequency of occurrence for each corresponding data

point in XList and YList. If freq is omitted, all values are used

once. If XList and YList are not specified, the default list

names are

L

1

and

L

2

. To access

Y

n

variables, press - }

2

.

QuadReg

[XList,YList,freq,Yn]

The LinReg(ax+b) line

The Manual-Fit line, Y

1

(see

example from that section)

Y

3

and Y

4

may vary.