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Select Analyze > Specialized Modeling > Fit Curve.
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Click OK.
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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, right-click 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.
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The curves appear S-shaped, 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.
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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.
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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.