ACCURACY AND PRECISION

ACCURACY AND PRECISION, CHTP 4 7
STATISTICAL TREATMENT OF DATA
True value or Most probable value
True value
 True value of a measurement is the value that would be obtained
by a perfect measurement




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 Thus true value can never be known with absolute certainty

94
Most probable value 70
56

 The average of the best results obtained by efficient and
19


experienced workers in many laboratories using different
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techniques or those obtained by using the most highly sophisticated
Y




instruments is the most probable value generally taken as the true
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AT




value.
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, Errors
 The difference between the true value and the measured value of a
quantity is known as error
 Error is also a mean of expressing the accuracy of a measurement.
Errors may be expressed as
 Absolute error
 Relative error




401
94
70
56
19
-9
Y
H
AT
EV
R




2