Page 35 - Statistics presented by Dr. Sara Ismail Aborass

9/8/2023

Sources of Systematic Error

B. Method Error

 Errors inherent in a method are difficult to detect and are thus the most serious
of the three types of determinate error.

 Slowness of some reactions.
 Incompleteness of the reaction.
 Possible occurrence of side reactions.
 Impurities in reagents.
Three approaches to minimise Method errors:
 Analysis of certified standards
 Use 2 or more independent methods
 Analysis of blank (without using sample)

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Sources of Systematic Error

C. Personal Error

Many measurements require personal judgements. Judgements of this type are
often subject to systematic, undirectional errors. For EXAMPLE,

 Color blindeness, i.e., insensitivity to color changes,
 Physical handicaps,
 Misuse of measuring devices,
 transfer of solution or incomplete ppt drying
 Preconceived idea of “true” value. (So do it blind)
Such errors can be reduced by self-discipline, experience ,and care of the analyst in

the physical manipulation.

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