98 Section 6: Statistics Functions

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 0gRto compute the y-intercept (A).

2.To compute the slope of the line (B) in RPN mode, press

1gR~d~-. To compute the slope of the line (B) in ALG mode, press these keys: 1gR~d-~}.

Example: Compute the slope and intercept of the regression line in the preceding

example.

Keystrokes (RPN mode)

0gR

Display

15.55y-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)

0gR

1gR~d-~}

Display

15.55y-intercept (A); projected value for x = 0.

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

File name: hp 12c pt_user's guide_English_HDPMF123E27

Page: 98 of 275

Printed Date: 2005/8/1

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