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Table of contents
Intro to regression
Nonlinear regression
Curve fitting with Prism
Interpreting the results
Comparing two curves
Distributions of best-fit values
Radioligand binding
Saturation binding
Competitive binding

Kinetics of binding

Dose-response curves
Enzyme kinetics
Standard curves


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Introduction
How to fit
Interpolating
Replicate unknowns
Troubleshooting
More information
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curvefit.com was created by GraphPad Software, Inc. Send comments or questions to the author of these pages, Dr. Harvey Motulsky, president of GraphPad Software.

In April 2003, GraphPad released Prism 4 and published Fitting Models to Biological Data using Linear and Nonlinear Regression. This book includes all the information that comprises curvefit.com, and much more. You can read this book as a pdf file.

Determining unknown concentrations from standard curves

To read values off the standard curve:

1. Enter the unknown values on the same table as your standard curve. Just below the standard curve values, enter your unknowns as Y without X. This example shows X and Y values for five standards, and Y values for four unknowns.

2. Click on the Graphs button, and look at a graph of your standard curve.

3. Click the analyze button, and choose how to fit the standard curve. Choose either linear or nonlinear regression, or create a LOWESS, Spline, or Point-to-point curve.

4. On the Parameters dialog, check the option to perform standard curve calculations.

5. Click on the Results button to see the tabular results. Drop down the View list and pick the standard curve.

6. Look at the table of X and Y values. The Y column contains values you entered, and the X column shows the calculated concentrations in the same units as you used for the X axis.

7. If necessary, transform the results to anitlogs. Click the Analyze button. On the New Analysis dialog, choose Transforms and choose to analyze the data you are looking at.

Standard curves with replicate unknown values


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