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Select Analyze > Modeling > Nonlinear.

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Click OK.

The Fit Curve Report appears as shown in Initial Fit Curve Report. The Plot report contains an overlaid plot of the fitted model of each formulation.
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To see a legend identifying each drug formulation, rightclick one of the graphs and select Row Legend. Select Formulation for the column and click OK. The plot shown in Fit Curve Report with Plot Legend appears.

The curves appear Sshaped, so a sigmoid curve would be an appropriate fit. Fit Curve Model Formulas shows formulas and graphical depictions of the different types of models that the Fit Curve personality offers.
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Select Sigmoid Curves > Logistic Curves > Fit Logistic 4P from the Fit Curve red triangle menu.

The Logistic 4P report appears (Logistic 4P Report). There is also a separate plot for each drug formulation. The plot of the fitted curves suggests that formulation B might be different, because the test B curve starts to rise sooner than the others. Inflection point parameters cause this rise.
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Select Compare Parameter Estimates from the Logistic 4P red triangle menu.

Notice that the Inflection Point parameter for the test B formulation is significantly lower than the average inflection point. This agrees with the plots shown in Logistic 4P Report. Drug formulation B has a lower toxicity ratio than the other formulations.
To launch the Nonlinear platform, select Analyze > Modeling > Nonlinear. The launch window is shown in Nonlinear Platform Launch Window.
Select the Y variable.
Select the X variable (selecting a column containing a model formula launches the Nonlinear platform, as explained in the Nonlinear Regression with Custom Models section).