(2) The value of knowing the distribution of a group of measurements
lies in the ability to predict the probable error of a single measurement.
(3) The purpose of repeated readings is to:
(a) Reduce the effect of random errors.
(b) Check for unsuspected variable.
(4) Methods of taking readings are as follows:
(a) Several readings over a short interval.
(b) Several readings with different ambient conditions.
(c) Several readings with different equipment.
(d) Arithmetic mean value.
The mean value of several readings
represents a more reliable value than any of the individual readings taken
alone.
A sufficient number of readings should be taken so that extremely
high and low values can be discarded.
(5) Significant figures are exactly what the term says: figures that
are significant in the expression of some magnitude or quantity.
Figures
that are not significant should be dropped and zeros substituted
(a) Significant digits.
1. The number of significant digits in a figure
can
be
determined from the way it is written. The following are examples:
2. It can be
seen from the example that zeros to the left of
the decimal point (00.1)
are not counted unless they are between digits
(630.8).
Also, zeros to
the right of the decimal place (9.001) are not
counted unless they follow
digits (3.00), (0.003), (300.010).
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