HP 12C, User Manual

Page: 98 / 288

98 Section 6: Statistics Functions
File name: HP 12c Pt Converted_user's guide_English_HDP0F123E02_080207 Page: 11 of 281
Printed Date: { 2007/8/2Dimension: 14.8 cm x 21 cm
Example: Check the reliability of the linear estimate in the preceding example by
displaying the correlation coefficient.
Keystrokes Display
~
0.90
The correlation coefficient is close
to 1, so the sales calculated in the
preceding example is a good
estimate.
To graph the regression line, calculate the coefficients of the linear equation
y = A + Bx .
1. Press 0
gR
to compute the y- intercept ( A ).
2. To compute the slope of the line ( B ) in RPN mode, press
1
gR~d~-
. To compute the slope of the line ( B ) in ALG mode,
press these keys: 1
gR~d-~}
.
Example: Compute the slope and intercept of the regression line in the preceding
example.
Keystrokes
(RPN mode)
Display
0
gR
15.55
y-intercept (A); projected value for x
= 0.
1
gR~d~-
0.001
Slope of the line ( B); indicates the
change in the projected values
caused by an incremental change
in the
x value.
Keystrokes
(ALG mode)
Display
0
gR 15.55
y-intercept (A); projected value for x
= 0.
1
gR~d-~} 0.001
Slope of the line ( B); indicates the
change in the projected values
caused by an incremental change
in the x value.
The equation that describes the regression line is:
y = 15.55 + 0.001x