54 Section 4: Statistics Functions

Example: Calculate the standard deviation about the mean calculated above.

Keystrokes

Display

 

S

31.62

Standard deviation about the mean nitrogen

 

 

application, x.

®1.24 Standard deviation about the mean grain yield, y.

Linear Regression

Linear regression is a statistical method for finding a straight line that best fits a set of two or more data pairs, thus providing a relationship between two or more data pairs, thus providing a relationship between two variables. By the method of least squares, ´L will calculate the slope, A, and y- intercept, B, of the linear equation:

y=Ax+B

1.Accumulate the statistics of your data using the zkey.

2.Press ´L. The y-intercept, B, appears in the display (X- register). The slope, A, is copied simultaneously into the Y- register.

3.Press ®to view A. (As is the case with the functions and S, L causes the stack to lift two registers if it's enabled, one if not).

T

Z

Y

X Keys:

t

z

y

x

y

x

A

B

´L

slope

y-intercept

®

y

y

B

A

y-intercept

slope

The slope and y-intercept of the least squares line of the accumulated data are calculated using the equations shown in appendix A.

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HP 15c Scientific manual Linear Regression, 31.62, Standard deviation about the mean nitrogen, Application