Distribution Fitting Software & Articles

Automated and Manual Distribution Fitting

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This tutorial explains how to automatically or manually fit distributions to your data using EasyFit.

Automated Distribution Fitting

The most common approach to fitting probability distributions to data is using the automated fitting capabily of EasyFit. This feature allows you to fit a large number of statistical distributions to your data in a batch, which is helpful if you have no or little information about the probability distribution you are trying to determine.

Bring In Your Data For Fitting

To analyze your data, you first need to bring it into EasyFit. You can either import your data from a file, paste the data from the Clipboard, or enter it by hand. For details on supported data formats and how to import your data into EasyFit, see How To Specify Your Input Data.

Specify The Distribution Fitting Options

Before EasyFit automatically fits distributions to your data, you can specify which distributions should be fitted exactly. EasyFit supports a large number of probability distributions, and you might want to fit all or some of them, depending on whether you have some additional information about your data. To specify the distributions you wish to fit, you can use the Distribution Fitting Options dialog (available from the Options|Fitting menu). There are some additional distribution fitting options you can specify, but in this tutorial we will focus on the basic options only:

Distribution Fitting Options

Click OK to close the dialog and choose Analyle|Fit Distributions from the main menu. EasyFit will ask you to specify your input data, then it will begin the distribution fitting process.

Once the distributions are fitted, EasyFit will order them accordingly to how well they fit to your data, based on the goodness of fit statistics:

Fitted Distributions

Now you can use the distribution graphs and goodness of fit tests to compare the fitted distributions and select the best model.

Manual Distribution Fitting

The manual fitting capability enables you to manipulate the fitted distributions in various ways - you can modify the distribution parameters, fit additional distributions, or remove them from the list of fitted models.

To fit a new distribution to your data, right-click the distribution list and select Add Distribution:

Adding a Distribution

EasyFit will display the list of available distributions, making it easy to select a particular model:

Distribution Fitting Options

Once you select a distribution, EasyFit will estimate its parameters and add it to the list of fitted models. The distribution parameters are displayed in a separate window which can be used to modify the parameter values:

Manual Distribution Fitting

Clicking the Apply icon will cause EasyFit to update the associated distribution graphs and goodness of fit reports according to the parameters you specify.

To remove one or several fitted distributions from the list, select them using the mouse, right-click the list, and choose Remove Distribution.