Errors in Chemical Analysis

Errors in Chemical Analysis - Chapt er 5 Er r or s in...

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Chapter 5: Errors in Chemical Analysis CHE 321: Quantitative Chemical Analysis Dr. Jerome Williams, Ph.D. Saint Leo University
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Overview Types of Errors in Data Random Errors Systematic Errors A Mean Calculation Using Excel
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Mean is arithmetic average of data set; evaluated as follows: Mean = Σ X i / N Median is the middle value of a data set when the data are arranged according to increasing or decreasing value Odd numbered Data Set: Median easily picked Even numbered Data Set: Take mean of middle pair Review Example 5.1
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Fig 5-1, p.91
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Accuracy is the closeness of a measured value X i to the true or accepted value X t Often expressed as either absolute error or relative error (percent, parts per thousand, or parts per million) Absolute Error (E) = X i - X t Relative Error (E r ) = (( X i - X t ) / X t ) * 100%
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Precision describes the reproducibility of
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This note was uploaded on 10/01/2011 for the course CHEM 3332 taught by Professor Thummel during the Spring '08 term at University of Houston.

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Errors in Chemical Analysis - Chapt er 5 Er r or s in...

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