Vernier Spectro Pro - Manual (Page 19)

How To
Spectro Pro 8
Curve Fit from the Analyze menu (or click on the Automatic Curve Fit
button on the toolbar). You will see the following dialog box. To fit to
just a part of your data, you must first select the desired portion of the
data by dragging across it.
Now choose a mathematical relation from the list at the lower left. You
may need to scroll through the list to find the appropriate function. The
polynomial choice also requires that you set the degree of the
polynomial. Next, choose the data set you want to use from the Perform
Fit On menu. Click on Try Fit to see the result. If you like, choose
another function or data column for another trial fit. You can also select
a different range of data by dragging across the graph region. Click on
Try Fit to see the new fit. Once you have a fit that you like, click on OK
to display the fitted curve on your graph. Click on Cancel to discard all
fits. The Save button will place the fitted curve on the main graph
window without closing the dialog box.
If you want a linear regression line to be forced through the origin, select
Automatic Curve Fit, from the Analyze menu and then select
Proportional. The Proportional fit (y=Ax) has a y-intercept value equal
to 0; therefore, this regression line will always pass through the origin of
the graph.
To superimpose a function over your data, make a graph active by
clicking on it once. Select Manual Curve Fit from the Analyze menu. In
the dialog box select a function. Adjust parameters as needed to fit the
function to your data.
Note that poorly chosen parameters may make the function miss the
graphed region entirely. In this case it is difficult to adjust the parameters
by trial and error. You may want to select parameters carefully so that the
function matches the data at the y-intercept, and adjust values from
there.
You can adjust either the number of significant digits or the number of
decimal places used in displaying fit statistics and parameters. After you
have completed a fit, double-click on the floating box containing the fit
Manual Fit
(Model Data)
Change Displayed Precision
of Fit Parameters