Sigmastat analysis features

Analysis Features

Regression Wizard

Solve a nonlinear regression problem with one of our 150 built-in fit equations or with a user-defined fit equation
Raw data for the regression can be selected from the worksheet using a variety of data formats or can be selected from a plot in a graph
The program’s default fit library contains models based on polynomials, rational functions, exponential growth and decay, sigmoidal functions, ligand binding, waveforms, logarithmic functions, probability distribution and density functions, piecewise linear and others
User-defined equations are created from the Regression Wizard using the Edit Function dialog and are saved to our default fit library. They can optionally be saved to any notebook file. An equation item in a notebook will launch the Regression Wizard when double-clicked
Fit model equations are coded with the Transform Language and can contain definitions of constants, weight variables, linear equality and inequality constraints and other variables
Initial parameter values required by the algorithm can be specified as constants or be defined using our automatic parameter estimation functions in the Transform Language
Fit equations can contain up to 500 parameters and up to 50 independent variables
Weighted regression is supported with weights defined as a constant per observation or as functions of the regression parameters. Weight functions permit the user to apply robust procedures for parameter estimation that mitigate the effects of outliers. Examples are given in the program’s fit library and the installed sample files
Options are available to create many types of results shown in the regression report or the worksheet.
Graphs of the best-fit equation with the raw data can be created for models with two or three independent variables. Confidence bands can be added
Models can be created to solve other type of problems besides ordinary data fitting. Examples are contained in the sample files and include global curve fitting, solving systems of equations, quantile regression and distribution fitting

Histogram Wizard

Plot Equation Dialog

Create the graph of a function in two or three dimensions
Enter a user-defined function or select an equation item from an equation library
Evaluate functions for specific values of the independent variable(s) or solve equations to obtain values for the independent variable for specified values of the dependent variable. Copy the results to paste to the worksheet, report or graph page

Transforms

Write your own numerical procedures, called Transforms, in the User-Defined Transform dialog. The Transform Language provides a vector-based computational environment with operations and functions that can manipulate worksheet data and perform many computations important to data analysis
Transforms can be saved as items in a notebook file or as separate files with the extension (.xfm). The installed program contains several(.xfm) files. Examples of computational procedures in these transforms include cumulative distribution functions, bootstrapping, peak finding, frequency tables, the D’Agostino-Pearson normality test and estimating the variance of functions of a random variable
The Transform Language is used in the Plot Equation dialog and the Regression Wizard to define Equation items in a notebook

Quick Transforms

You can use the Quick Transform dialog for quickly creating and computing single-line transforms
The dialog supports column picking and a functions palette to create transforms easily. The output columns from a quick transform can be titled with the transform itself for later reference
Quick transforms are saved with the worksheet they use for their output
The output of a quick transform can be updated automatically for changes in the input data