|Developer(s)||Centers for Disease Control and Prevention|
|Stable release||3.5.1 / 2008-08-18|
|Written in||Visual Basic .NET|
|Available in||4 languages|
|Type||Statistical software, epidemiology|
Epi Info has been in existence for over 20 years and is currently available for Microsoft Windows. The program allows for electronic survey creation, data entry, and analysis. Within the analysis module, analytic routines include t-tests, ANOVA, nonparametric statistics, cross tabulations and stratification with estimates of odds ratios, risk ratios, and risk differences, logistic regression (conditional and unconditional), survival analysis (Kaplan Meier and Cox proportional hazard), and analysis of complex survey data. The software is in the public domain, free, and can be downloaded from http://www.cdc.gov/epiinfo. Limited support is available.
An analysis conducted in 2003 documented over 1,000,000 downloads of Epi Info from 180 countries.
Epi Info has been in development for over 20 years. The first version, Epi Info 1, was originally implemented as an MS-DOS batch file on 5.25" floppy disks and released in 1985. MS-DOS continued to be the only supported operating system until the release of Epi Info 2000, which was written in Microsoft's Visual Basic and became the first Windows-compatible version. The last MS-DOS version was Epi Info 6.04d, released in January of 2001.
Epi Info 2000 changed the way data was stored by adopting the Microsoft Access database format, rather than continuing to use the plain-text file format from the MS-DOS versions. Following the release of Epi Info 2000 was Epi Info 2002, and then Epi Info version 3.0. The 3 series is the presently-maintained Epi Info product line. It should be noted that Epi Info 3 for Windows is different than Epi Info 3 for MS-DOS, even though they share the same version number.
The next iteration of the Epi Info series, Epi Info 7, was made open source on November 13, 2008 when its source code was uploaded to Codeplex for the first time.
From a user's perspective, one of the most important functions of Epi Info is the ability to rapidly develop a questionnaire, customize the data entry process, quickly enter data into that questionnaire, and then analyze the data. For epidemiological uses, such as outbreak investigations, being able to rapidly create an electronic data entry screen and then do immediate analysis on the collected data can save considerable amounts of time versus using paper surveys.
Epi Info uses three distinct modules to accomplish these tasks: MakeView, Enter, and Analysis. Other modules include the Report module, a mapping module, a menu module, and various utilities such as the NutStat program.
Electronic questionnaires, also known as "views" in Epi Info terminology, are created in the MakeView module. Individual questions can be placed anywhere on the screen and across multiple pages, with the user given complete control over appearance and function. The user defines both the question's prompt and the format of the data that is to be collected. Data types include numbers, text strings, dates, times, and yes/no. Users can also create drop-down lists, code tables, and comment legal fields. One of the more powerful features of MakeView, however, is the ability to create "check code". Check code allows for certain events to occur depending on what action a data entry person has taken as they are typing. For example, if a user enters "Male" into a question on gender, any questions relating to pregnancy might then be hidden. Skip patterns can also be created so that if a user enters "No" to a question on whether or not they smoke, the cursor skips past any fields related to smoking. Relational database modeling is supported, as users may link their view to any number of other views in their database.
The Analysis module is where users analyze their data. Import and export functions exist that allow for file types to be converted between plain-text, CSV, Microsoft Excel, Microsoft Access, dBase, FoxPro, and other formats. Many advanced statistical routines are provided, such as t-tests, ANOVA, nonparametric statistics, cross tabulations and stratification with estimates of odds ratios, risk ratios, and risk differences, logistic regression (conditional and unconditional), survival analysis (Kaplan Meier and Cox proportional hazard), and analysis of complex survey data.
Using the Epi Map module, data can be displayed either by geographic reference or by GPS coordinates. The Report module allows the user to edit and format output from various Epi Info tools and modules. The resulting HTML document can then be printed or emailed to others.
The menu module allows for the editing and re-arranging of the basic Epi Info menu structure. This module is powerful enough that several applications have been built off of it, including the National Electronic Telecommunications System for Surveillance (NETSS) for Epi Info 6. Unlike the other modules, the menu module does not have a user interface, but instead resides in a .mnu file whose scripts must be edited manually.
NutStat is a program that records and evaluates measurements of length, stature, weight, head circumference, and arm circumference for children and adolescents. It calculates percentiles, number of standard deviations from the mean (Z-scores), and in some cases, percent of median, using either the CDC/WHO 1978 or CDC 2000 growth reference curves.
Version 7 is currently in development as an open-source project, written using Microsoft's C# .NET programming language. Both the Windows and Linux operating systems are supported. Source code distribution and contribution currently takes place through Codeplex. Unlike previous versions of Epi Info, however, version 7 will come in one of two flavors: The CDC Edition and the Community Edition. The Community Edition will be edited and modified by the community at large, while the CDC Edition will be maintained by the Epi Info development team. Over time, the CDC Edition will incorporate changes and improvements that have been made to the Community Edition and put them through CDC's software verification process. CDC approval will ensure that the CDC Edition can be authorized for installation on U.S. government computer systems.
MySQL and SQL Server databases will be supported as the database backends for version 7, in addition to the traditional Microsoft Access database format. Users will also have the option of storing metadata separately from the data itself; for example, one might store the questionnaire in an XML file, while storing collected data in a MySQL database. A conversion utility will allow existing Epi 3 projects to be made compatible with version 7.
Initially, only the MakeView, Enter, and Analysis modules will be available with Epi Info 7. Epi Map, Epi Report, and the ability to edit the menu will be added later.
|Series||Version||Operating System Support||Support status||Release date||Significant changes|
|Epi Info for DOS||1||MS-DOS||1 Sep 1985|
|2||MS-DOS||20 Aug 1986|
|4.1||MS-DOS||15 Nov 1988|
|5.01||MS-DOS||Oct 1990||Allowed European date formats and non-English characters in data fields.|
|6.0||MS-DOS||1992||Added programmable menu system|
|6.04c||MS-DOS||1998||Year 2000 compatibility upgrade|
|Epi Info 2000||2000 1.1.2||Windows 9x, NT 4.0, 2000||2 Nov 2001||First Windows-compatible version of Epi Info.|
|2002 R2||Windows 9x, NT 4.0, 2000, XP||30 Jan 2003|
|Epi Info 3||3.0||Windows 9x, NT 4.0, 2000, XP||n/a|
|3.01||Windows 9x, NT 4.0, 2000, XP||3 Nov 2003|
|3.2||Windows 9x, NT 4.0, 2000, XP||4 Feb 2004|
|3.2.2||Windows 9x, NT 4.0, 2000, XP||14 Apr 2004|
|3.3||Windows 98, NT 4.0, 2000, XP||5 Oct 2004||Windows 95 no longer supported, case-based mapping functionality added to the Analysis MAP command.|
|3.3.2||Windows 98, NT 4.0, 2000, XP||9 Feb 2005|
|3.4||Windows 98, NT 4.0, 2000, XP||30 Apr 2007||Ability to use standard ISO date formats, disallowed multiple instances of the Anaysis module, added ability to run reports from Analysis, and CDC flags added to the Nutrition module.|
|3.4.1||Windows 98, NT 4.0, 2000, XP||9 Jul 2007||Added a right-to-left language controller in Analysis|
|3.4.2||Windows 98, NT 4.0, 2000, XP||20 Sep 2007|
|3.4.3||Windows 98, NT 4.0, 2000, XP||17 Oct 2007|
|3.5||Windows 98, NT 4.0, 2000, XP SP3||9 Jun 2008||Added feature to use standardized vocabularies. First version to require Service Pack 3 if running Epi Info on a computer with Windows XP.|
|3.5.1||Windows 98, NT 4.0, 2000, XP SP3, Vista||13 Aug 2008||First version compatible with Windows Vista. This version also fixed compatibility for languages that are read right-to-left.|
|Epi Info 7||7.0.5 (Alpha)||Windows XP SP3, Vista, Ubuntu||5 Jan 2009||Programming language changed to Visual C# .NET; MySQL and SQL Server database support added; XML meta-data support added; Linux compatibility added; first Windows version of Epi Info to be open source.|