With improvements in commercial software, such as SAS, SPSS, Stata, and others, is there still a need for free epidemiologic software?  Commercial software can be expensive, may have a steep learning curve, and may not provide certain types of desired analyses.  In this article information on three free epidemiologic/statistical programs is provided: Epi Info, OpenEpi, and WinPepi.   

Epi Info 7.1.2 

Epi Info is a free program available from the Centers for Disease Control and Prevention, Atlanta, GA (www.cdc.gov/epiinfo).  The program allows the creation of data entry systems and the analysis of data.  Version 7 of Epi Info can be copied onto a Windows-based computer without the need to run an install and can be run from a thumb drive.  Version 7 is a complete rewrite of the previous Version 3 of the program with a number of improvements.   This is a version of Epi Info that appears to be bringing back epidemiologists to using Epi Info. 

OpenEpi 3.01 

OpenEpi (www.OpenEpi) is a free, web-based, open source, operating system-independent series of programs for use in epidemiology, biostatistics, public health, and medicine, providing a number of epidemiologic and statistical tools for summary data. OpenEpi was developed in JavaScript and hypertext markup language (HTML) and can be run in browsers supporting these languages, such as Microsoft Internet Explorer, Mozilla Firefox, Safari, Chrome, and Opera, and on a number of operating systems, such as Microsoft Windows, Macintosh, Linux, and Android tables and smartphones. The program can be run from the OpenEpi website or downloaded and run without a web connection. The source code and documentation is downloadable and freely available. OpenEpi has had almost 10 million hits since its inception in 2003, with over 2 million hits in 2012 alone from 188 countries. 

Updates in Version 3.01 include

·         In addition to English, French, Italian, and Spanish, OpenEpi can now be run in Portuguese

·         The program has been modified so it can be used with greater ease on smartphones and tablets

·         Added epidemiologic and statistical tests

·         The output from a module is all stored in one HTML file during calculations.  For example, if several sample size calculations are performed for various scenarios, all of the output is placed in one output HTML file. 

WinPepi 11.32

WinPepi ( www.brixtonhealth.com ) is a free 'Swiss army knife' set of seven Windows-based programs (comprising 124 modules) that provide most of the statistical procedures commonly used in the planning and analysis of epidemiological studies (including meta-analyses), in teaching programs on statistics in epidemiology, and in clinical epidemiological practice. It also includes many procedures that are less commonly used or not very easily found, such as the capture-recapture method, appraisal of the effects of misclassification, multiple significance tests, and unmeasured confounders, the assessment of inter-rater and intra-rater reliability, the use of Bayes factors to appraise whether associations are worthy of note, and estimation of the probability that an effect will be replicated in other studies. 

A 'portal' permits easy identification of, and access to, the required modules. WinPepi is user-friendly, provided that users focus on the specific modules and results that interest them, and disregard the many others.  The programs are accompanied by extensive manuals that discuss the uses, limitations and applicability of the procedures, and furnish formulae and references. WinPepi does not provide data-management facilities; it usually requires previously-summarized data, entered at the keyboard or pasted from a text file or spreadsheet. The programs can be run from a portable device such as a USB flash drive. The latest version is 11.32.

Other Statistical Packages

A fairly comprehensive listing of statistical packages can be found at:  http://tinyurl.com/nw9ka2o
with a comparison of software programs available here: 
http://tinyurl.com/bd9j44 

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