Manual

Statistics 2Var app 231
Defining a regression model
You define a regression model in Symbolic view. There are
three ways to do so:
• Accept the default option to fit the data to a straight
line.
• Choose a pre-defined fit type (logarithmic,
exponential, and so on).
• Enter your own mathematical expression. The
expression will be plotted so that you can see how
closely it fits the data points.
Choose a fit 1. P r e s s
Y
to display the Symbolic view.
2. For the analysis you are interested in (S1 through S5),
select the
Type field.
3. Tap the field again to see the menu of fit types.
4. Select your preferred fit type from the menu. (See “Fit
types” on page 231.)
Fit types Twelve fit types are available:
Fit type Meaning
Linear (Default.) Fits the data to a
straight line: y = mx+b. Uses a
least-squares fit.
Logarithmic Fits the data to a logarithmic
curve: y = m lnx + b.
Exponential Fits the data to the natural
exponential curve: .
Power Fits the data to a power curve:
..
Exponent Fits the data to an exponential
curve: .
Inverse Fits the data to an inverse
variation:
ybe
mx
=
ybx
m
=
ybm
x
=
y
m
x
----
b+=