1. Orthogonal tables with respect to a model

1.1 What is a model?

After selecting the factors considered to have an influence on the experiment's response, the experimenter proposes a model corresponding to the hypothesis that seems most likely.

The model is, in general, a linear expression of the response variable as a function of the factors and interactions assumed to have an effect on the response. The coefficients of the model can only be calculated after the experiments have been carried out. In the absence of these coefficients, we write the model symbolically to specify the factors and interactions taken into account.

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