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Fitting a curve to 2var data, Regression coefficients – HP 38g Graphing Calculator User Manual

Page 127

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Fitting a Curve to 2VAR Data

In the Plot view, press

{{FIT}}

to turn on

{{FIT«}}.

This

calculates a curve to fit the checked two-variable data set(s).

I PLOT I {{MENU}} {{FIT}}

(assuming 2VAR is set and
two data sets are defined and
checked in Numeric and

Symbolic views)

SYMB

The expression in

Fit

1

shows that the slope=0.03865

and they-intercept=4.856.

i^^STATISTICf fVMEDLIC VIEH^W

.'Sl:C3

C4

S2!

Fit2!m*X+b

f

EHTER U;Eli DEFINED FIT__________________

Regression Coefficients

As shown above, the

{{FIT«}}

mode (in Plot view) calculates

and draws a curve to fit the data points using the given

regression model. It also substitutes calculated values for the

regression coefficient variables in the Fit expression.

CORK

CORK, the

correlation coefficient,

is a measure of fit to a

linear

curve only. Regardless of the Fit model you have chosen,

CORR relates to the linear model.

Relative Error The

relative error

is stored in a variable named RelErr. The

relative error provides a measure of fit accuracy for all fits,

and it

does

depend on the Fit model you have chosen.

The relative error is a measure of the error between predicted

values and actual values based on the specified Fit. A smaller

number means a smaller error, which means a better fit.

Statistics S21