Box 4-1 Analytical Chemistry and the Law

As a person who will either derive or use analytical results, you should be aware of this warning 3 

Analytical chemists must always emphasize to the public that the single most important characteristic of any result obtained from one or more analytical measurements is an adequate statement of its uncertainty interval. Lawyers usually attempt to dispense with uncertainty and try to obtain unequivocal statements therefore, an uncertainty interval must be clearly defined in cases involving litigation and/or enforcement proceedings. Otherwise, a value of 1.001 without a specified uncertainty, for example, may be viewed as legally exceeding a permissible level of 1. 

Some legal limits make no scientific sense. The Delaney Amendment to the U.S. Federal Food, Drug, and Cosmetic Act of 

The F test tells us whether two standard deviations are significantly different from each other. F is the quotient of the squares of the standard deviations  

We always put the larger standard deviation in the numerator so that F 1. If Fca)cu aled Ftab)e in Table 4-4, then the difference is significant. 

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