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ICT IN BIOLOGY
MS-EXCEL: GOING FURTHER WITH GRAPHS i: TREND LINES
(CONTINUED)
This tutorial is available as a pdf download
A series of lines will be
presented. Select the one which looks the most
appropriate and fits the data best. This may take a
few trials.
In this example the trend line
permits us to do two things:
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First we can see how well the
points fit the line. The scatter of the points either
side of the line shows how much variation there is in
the data. This is a measure of the uncertainty.
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Second we can use the curve to
estimate the optimum temperature of this enzyme. The
fact that one of points (40°C) had to be excluded as
an outlier will mean this estimate is less sure as it
is near a critical part of the curve.
 Some
graphs do not permit a trend line to be drawn in Excel,
the points do not fit one of the program’s equations.
Here it is necessary to draw a line by hand using the
Draw
tool bar after the graph has been cut and pasted into
MSWord.
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