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Chapter 7: Statistical Data Treatment & Evaluation
CHE 321: Quantitative Chemical AnalysisDr. Jerome Williams, Ph.D.
Saint Leo University
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Overview
• Statistical Testing to Data Treatment– Confidence Intervals
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Statistical Testing to Data Treatment
• The confidence interval for the mean is the range of values within which the population mean (μ) is expected to lie with a certain probability.
• The confidence level is the probability that the true mean lies within a certain interval. It is often expressed as a percentage.
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Statistical Testing to Data Treatment
• Calculating a confidence interval (CI)
• CI for μ = mean ± (zσ / √N )
• Equation applies only if we can assume that s is a good approximation of σ.
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Figure 7-1 p125
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Figure 7-1a p125
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Figure 7-1b p125
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Figure 7-1c p125
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Figure 7-1d p125
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Figure 7-1e p125
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Table 7-1 p125
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Table 7-2 p125
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Statistical Testing to Data Treatment
• Suppose we consider the case where s is not a good approximation of σ.
• To account for this, we often use the t-test.
• Calculating a confidence interval (CI)
• CI for μ = mean ± (ts / √N )
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Table 7-3 p127