The Reactor Half Fraction.jmp sample data table contains the results of an experiment derived from a design discussed in Box et al. (1978). You are interested in identifying significant effects in a model that contains main effects and two-way interactions. This example uses a model with fifteen parameters for a design with sixteen runs. The example illustrates the analysis both with the Fit Two Level Screening Platform and the Fit Model Platform.
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Select Analyze > Specialized Modeling > Specialized DOE Models > Fit Two Level Screening.
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The effects that have an individual p-value less than 0.10 are selected.
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A t-ratio is calculated using Lenth’s PSE (pseudo-standard error). The Lenth PSE value is shown below the Half Normal Plot.
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Both individual and simultaneous p-values are shown. Those that are less than 0.05 are shown with an asterisk.
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In this example, Catalyst, Temperature, and Concentration, along with two of their two-factor interactions, are selected. Alternatively, you can fit the same model in the Fit Model Platform.
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Since there are 16 observations and 16 model terms, there are not enough observations to estimate an error term. Without an estimate of error, it is not possible to conduct standard tests. Parameter estimates are provided, but because there are no degrees of freedom for error, standard errors, t-ratios, and p-values are all missing. This illustrates the strength of the Fit Two Level Screening platform for getting the most information out of a screening design.