文档介绍：Chapter 2 Data Handing and Error
§ Error in Analytical Chemistry
§ The Data Distribution
§ Statistics Process
§ Significant figures
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VOCABULARY
Precision 精确度 Accuracy 准确度
Normal distribution 正态分布(((or Gaussia curve)
Random error 随机误差 Key Number 级数
Absolute error 绝对误差 Mean Error 平均误差
Relative error 相对误差 Degree of Freedom 自由度
Standard deviation 标准偏差 Variance 方差
Systematic Error 系统误差 Mean 平均数
Median 中间数 Significant Number 有效数字
Parameter 参数 Mean deviation 平均偏差
Data handling 数据处理 Distribution 分布
Statistical Handling 统计处理
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§ Error in Analytical Chemistry
Error and Accuracy
1. Error ——The different between determination xi and
μ true value.
E (Absolute Error ) 表示。
E = xi-μ
RE ( Relative Error )))
x −µ
RE = i ×100 %
µ
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2. Accuracy and Error
The smaller the error is, the
higher the accuracy is.
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g g,
g g,
Absolute Error :
( -) g = - g
( -) g = - g
Relative Error :
−
×100 % = − %
−
×100 % = − %
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Deviation and precision
1. Deviation
The different between xi and mean.
= −
Abosolute di: d i xi x
Relative di:
x − x
d = i ×100 %
r x
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Average Deviation :
n n
= 1 = 1 −
d ∑d i ∑ xi x
n i=1n i = 1
Relative Average Deviation :
d
d = ×100 %
r x
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2. Standard Deviation
Population Standard Deviation
σ n
∑(x −µ)2
= i=1
n
Sample Standard Deviation
n
− 2
∑(xi x)
s = i=1
n -1
Freedom f= n-1
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2
n
x
n ∑ i
=
∑ x 2 − i 1
= n
s = i 1
n −1
sr : Relative Standard Deviation
s
s = ×100 %
r x
又称为变异惻系数 CV (Coefficient of Variation )。
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3. Precision
Repeatability(r):The results were
obtained by same operator in same condition.
Reproducibility (R): The results were
obtained by different operator in different
condition.
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