74
35. Press the
DOWN ARROW key. The display will show:
36. Press
ENTER. The display will show:
37. Press
ENTER. The display will show:
F0 means Formula 0, which is a point-to-point (piecewise) calibration
curve. A best-fit line is not possible when using this type of curve, so
a correlation coefficient (r
2
) is not applicable (n/a). See Figure 18,
Calibration Curve.
38. Press the
DOWN ARROW. The display may show (for example):
F1: r
2
= 0.99530 or F2: r
2
=0.99322or F3: r
2
=0.99212
F1 denotes linear equation. F2 means a quadratic equation and F3
denotes a cubic equation. To view the r
2
value of the alternative
equations, press the
UP ARROW key.
Important Note: Selection of the best calibration curve should not be based
solely on the r
2
value. While a quadratic or cubic may have a r
2
value closer to
1.000, it may not be an appropriate fit for the data. There is no substitute for
printing out or manually graphing the calibration curve and visually inspecting it to
see how it fits the data.
39. Press ENTER to accept the type of calibration curve.
The display will show (for example):
nm
+8.8.:8.8.
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
888450
*
Calib Formula:F0
nm
+8.8.:8.8.
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
888450
*
F0: C=Piecewise
nm
+8.8.:8.8.
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
888450
*
F0: r= n/a
nm
+8.8.:8.8.
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
888450
*
F1: C=a+bA
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