These are in the same units as the X values, so are the logarithm of concentration. The X column of the results table has the interpolated values we want.
For this example, we aren't too interested in these results. It tabulates the best-fit values of the parameters and much more. The second page is the table of results for the overall curve fit. The first page shows you the interpolated values. Note that 4PL means four parameter logistic, which is another name for this kind of equation.įor this example, leave all the other settings to their default values.Ĭlick OK to see the curves superimposed on the graph. Choose a modelĬhoose the equation: Sigmoidal, 4PL, X is log(Concentration). Choose the standard curve analysisĬlick the Analyze button and from the list of XY analyses choose: Interpolate a Standard Curve.Īlternatively, you can click the “Interpolate a standard curve” button right on top of the Analyze button. Since the unknowns have no X value, they are not included on the graph. You can also choose to plot the individual duplicates rather than plot the means.
You can customize the symbols, colors, axis labels, etc. The graph Prism makes automatically is fairly complete. So a concentration of 1 micromolar (10 -6 Molar) would be entered as -6. Why are X values negative? Because in this example, the X values are the logarithm of concentrations expressed in molar. Note that three of the four unknowns are labeled, so you can later match up the results with the labels. The goal of this analysis is to interpolate the corresponding X values (concentrations) for these unknowns. These have a Y values that you measured, but no X. The first seven rows contain the standard curve, in duplicate.
You can move the floating note out of the way, or minimize it. The sample data may be partly covered by a floating note explaining how to fit the data (for people who are not reading this help page). Interpolate unknowns from sigmoidal curve. From the Welcome or New Table dialog, choose to create an XY data table, and select the sample data set: RIA or ELISA.
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