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Web Pages that Perform Statistical Calculations!
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(Updated 12/20/2015 -- Updated link to Soren Merser's Survival Analysis page, and added a link to his new Cox Regression page,)

Precision Consulting -- Offers dissertation help, editing, tutoring, and coaching services on a variety of statistical methods including ANOVA, Multiple Linear Regression, Structural Equation Modeling, Confirmatory Factor Analysis, and Hierarchical Linear Modeling. If you're stuck on your proposal, methodology, or statistical phase of your dissertation, you might want to contact them.

The web pages listed below comprise a powerful, conveniently-accessible, multi-platform statistical software package. There are also links to online statistics books, tutorials, downloadable software, and related resources. 

These pages are located on servers all over the world, and are the result of much cleverness and hard work on the part of some very talented individuals. So if you find a page useful it would be nice to send the authors a short e-mail expressing your appreciation for their hard work and generosity in making this software freely accessible to the world.

Table of Contents for this page...

Other Statistical Resources...

First -- Choose the right test! [return to Table of Contents]

There are a bewildering number of statistical analyses out there, and choosing the right one for a particular set of data can be a daunting task. Here are some web pages that can help:

  1. Statistical Decision Tree, from the developers of the MicrOsiris package. This is an interactive set of web pages to help you select the right kind of analysis to perform on your data. It asks you a simple series of questions about your data (how many variables, etc.), then makes recommendations about the best test to perform.
  2. Choosing a Statistical Test, Chapter 37 of Dr. Harvey Motulsky's book Intuitive Biostatistics.
  3. "Selecting Statistics", by Bill Trochim (Cornell). Another  interactive set of web pages to help you select the right kind of analysis to perform on your data.

"Online Software Package" web sites [return to Table of Contents]

As you can see from looking at the web site, there are many "stand-alone" web pages that are each designed to perform only a single test or calculation. In addition, some talented individuals and groups have created coherent website that perform an entire suite of calculations, with a logical organization and consistent user interface. Each of these web sites is really a fairly complete online statistical software package in itself. Here are some of these "comprehensive" statistical analysis web sites:

Calculators, Plotters, Function Integrators, and Interactive Programming Environments...[return to Table of Contents]

Probability Distribution Functions: Tables, Graphs, Random Number Generators... [return to Table of Contents]

Descriptive Statistics, Histograms, Charts... [return to Table of Contents]

Confidence Intervals, Single-Population Tests, Measurement Errors... [return to Table of Contents]

Sample Comparisons: t-Tests, ANOVAs, Non-parametric Comparisons... [return to Table of Contents]

Contingency Tables, Cross-tabs, Chi-Square Tests... [return to Table of Contents]

Regression, Correlation, Least Squares Curve-fitting, Non-parametric Correlation... [return to Table of Contents]

Analysis of Survival Data... [return to Table of Contents]

Bayesian Methods... [return to Table of Contents]

Other Statistical Tests and Analyses... [return to Table of Contents]

Specialized and Discipline-Specific Tests and Analyses... [return to Table of Contents]

Power, Sample Size and Experimental Design Calculations... [return to Table of Contents]

Check out the web site, which contains (at last count) 19 interactive calculators for power or  required sample size for many different types of statistical tests: testing 1 mean, comparing 2 or more means, testing 1 proportion, comparing 2 or more proportions, testing odds ratios, and two 1-sample tests (normal and binomial-based). This site also provides calculators for non-inferiority and equivalence studies. The web pages display graphs that dynamically show how power varies with various design parameters as you change other parameters.

Also, look at the very general and elegant power/sample-size calculator by Russel Lenth (U of Iowa). It handles tests of means (one or two samples), tests of proportions (one or two samples), linear regression, generic chi-square and Poisson tests, and an amazing variety of ANOVAs -- 1-, 2-, and 3-way; randomized complete-block; Latin and Greco-Latin squares; 1-stage, 2-stage, and factorial nested designs; crossover; split-plot; strip-plot; and more! This calculator is implemented in Java, and can be run as a web page, or can be downloaded to your computer to run offline as a stand-alone application.

Here's a collection of online power calculator web pages for specific kinds of tests:

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