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
Y2, if desired.
&
QuadReg QuadReg -
v
!
6 6
QuadReg (quadratic regression) fits the second-degree
polynomial y=ax2+bx+c to the data. It displays values for a, b,
and c; when DiagnosticOn is set, it also displays a value for r2
(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 L1 and L2. To access Yn variables, press - } 2.
QuadReg [XList,YList,freq,Yn]
The LinReg(ax+b) line
The Manual-Fit line, Y1 (see
example from that section)
Y3 and Y4
may vary.