Chemical mixture experiments experimental design

Chemical mixture experiments have distinct characteristics that can preclude the use of traditional statistical analysis techniques. Mixture experimentation often poses unique exploratory questions that can be answered efficiently and economically with non-traditional statistical techniques. General statistical guidelines stress the importance of design, preliminary studies, action levels of variables, graphics, and appropriate statistical testing. Fractional ctorial and Simplex designs are just two of many statistical tools that are useful for analyses of mixture experiments. 

The mixture design is a class of experimentation that is different from the previous designs we have discussed, wherein the assumption is that all factor levels are independent. In the case of the mixture design, there is an assumed relationship among factors. Suppose that in a chemical mixing experiment of two chemicals, the experimenter would like to test how the quantity of each chemical affects the properties of mixed chemical. In this case, we use the previous design. However, if the experimenter would like to study the effect of chemical ratio of two substances such as 1 1 or 2 3, a mixture design is used under a constraint that summation of the ratio must be equal to 1 [57]. 

An essential consideration in experimental work is safety. This includes issues of toxicity, flammability, etc., for all chemicals involved, and also hazards created by interactions within mixtures. Safety must be considered at all stages in the design and construction of experiments. 

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