Page 21 - Quality control of pharmaceuticals (07-PA 704)
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analysis of blank
3. Personal Error
Many measurements require personal judgements subject to systematic,
undirectional errors.
Example:
Color blindeness, i.e., insensitivity to color changes
Physical handicaps
Misuse of measuring devices
Preconceived idea of “true” value.
Such errors can be reduced by self-discipline, experience ,and care of the
analyst in the physical manipulation.
The Effect of Determinate Errors Upon Analytical Results
Determinate errors may be either constant or proportional.
Constant (Additive) Errors:
The absolute error is independent of the magnitude of the measured
quantity, thus of the size of the sample.
Absolute error become more serious as the size of the quantity
measured decreases. Thus the relative error varies.
