System Components (Modules)

Form Designer

As a suite of tools for collecting and analyzing- data, Epi Info™ 7 must support the creation of smart data entry forms that facilitate systematic data collection and perform data validation in real time. These steps are accomplished using Form Designer.  This module's functionality can be divided into two components.  First, Form Layout supports project origination, the structure and relationship of forms, and the selection and positioning of data entry fields on pages, their properties and tab order. Second, Check Code, specifies  the needed input validation, skip patterns, automatic calculation of data, and intelligent field navigation.

Starting with an empty canvas, the user can select data-entry fields including text fields, pull-down menus, check boxes, and radio buttons, as well as a graphic, calendar-driven fields for entering dates and auto-formatting fields for entering data such as phone numbers and times. Titles and supporting text can be added to the form; data fields can be grouped, arranged, and aligned to enhance the form's readability and aesthetics.  A form can contain one or more pages, each corresponding to a database table to be populated using the Enter (data entry) module and processed by Classic Analysis or Visual Dashboard. 

Enter

The Enter module is the primary mechanism for data entry in Epi Info™ 7. Using the data table or tables constructed when the form was created and any subsequent check code added to the form, Enter can be used to enter new data, modify existing data, or search for records.  The Find function allows records to be located that match values specified for any combination of variables on the form. In Enter, the cursor moves from field-to-field and then page-to-page, flagging invalid data according to the user-defined check code rules (if any) and then automatically saving data. Navigation buttons provide access to new, previous, next, first, and last records, as well as to their related tables, if any.  The user can also return to Form Designer to edit the form and jump ahead to Classic Analysis or Visual Dashboard for data analysis, visualization, and reporting.

Classic Analysis

The Epi Info™ 7 Classic Analysis (CA) module is used for the statistical analysis of data. Data to be analyzed may be collected using questionnaires created in Form Designer and populated using Enter or may be imported from external sources. It is the core analytical component of Epi Info™ 7 and has remained largely unchanged in form and function through many versions and implementations of the package. The user can execute commands from the interactive, menu-driven Command Explorer or the text-based Program Editor. Output is generated in HTML format and organized by a paging system that allows users to navigate forward and backward through the results using anchors embedded in the output of each command. The Explorer lists 46 commands organized into groups according to function: manipulation of datasets, individual variables, statistical analyses, defining new commands and generating output. A user can create a sequence of commands representing a complex workflow in the Program Editor, save it as a file and execute it in batch mode, independently of the Classic Analysis GUI.

Visual Dashboard

The Epi Info™ Visual Dashboard complements Classic Analysis with a more modern, graphically-oriented interface for configuring analytical tools and displaying their results. Whereas the largely text-based output of Classic Analysis accumulates in a scrolling output page, with HTML anchors to facilitate navigation, the analytical tools in Visual Dashboard, known as "gadgets", are intended to be positioned on a canvas, like gauges on a dashboard, allowing the user to take in the status of the project in a single view. While Visual Dashboard does not support programming for automated processing, the ability to update the analyses (with a single button-click) when new data becomes available, eliminates the need for it, in all but the most sophisticated use cases.

The requirements for this module are divided into three sections. Navigation covers the Toolbar and Status Bar, located at the top and bottom, respectively, of the Visual Dashboard window. Canvas discusses the requirements for functionality residing in the Dashboard itself. The final section, Menu Commands, covers the tools accessed from the master menu including populating the canvas with gadgets, charts, and calculators, as well as loading and saving canvas and project data. In many cases, there are multiple ways to access a given functionality between, and even within, the canvas and Toolbar. The first two sections indicate how the various functions are accessed; Menu Commands describes the functions in detail.

Epi Map

The Epi Info™ Map module enables the user to plot the locations associated with study data on a global coordinate system overlaid with geophysical ("satellite") or geopolitical ("streets") maps. The street and satellite maps are, in essence, built-in Base Layers that supply geographic reference information onto which study data can be layered. User-defined Base Layers can be provided in the form of local shapefiles or remote data from KML/KMZ files or a map server on the Internet. Study data is applied in Data Layers, which can be divided into two groups. Both choropleth and dot density maps associate quantitative data with map regions, such as those defined in shapefiles or Keyhole data files. These map layers are useful for displaying large-scale public health information, where the number of cases, for example, is represented by color of, or dot density in, the jurisdictions drawn on the map. The other Data Layer group, consisting of case-cluster and spot maps, uses latitude and longitude to map the locations of subjects or other physical entities relevant to the study. The coordinates may be entered from GPS units in the field or translated from street addresses by the Check Code command GEOCODE. The user can also add markers, labels, and zones manually, by clicking on the map display.

StatCalc

The StatCalc component of Epi Info™ 7 enables the user to evaluate the performance of different study designs and statistical tests by supplying high-level information on the properties of hypothetical data sets and the criteria used for evaluation. StatCalc tools can be divided into three broad categories: 1). sample size and power calculations for unmatched case-control studies, population surveys, cohort or cross-sectional studies, chi-square for trend by the Mantel extension of the Mantel-Haenszel summary odds ratio, and chi square (tests for the presence of a trend in dose-response or other case-control studies where a series of increasing or decreasing exposures is being studied); 2). analysis of 2×2 tables to produce odds ratios and risk ratios (relative risks) with confidence limits, Fisher exact tests, and 1- and 2-tailed p-values, with Mantel-Haenszel summary odds ratios, chi square tests and associated p-values for stratified data; 3). distribution-based event probabilities, 2-tailed p-values and confidence intervals for deviations from binomial (proportions) and Poisson (rare events) distributions given the number of observed and expected events. The StatCalc tools can be accessed as an independent module from the main menu or as part of the Visual Dashboard.

System Configuration

Epi Info™ 7 has several mechanisms that allow the user to configure the system, set options and defaults, and get help with program usage. The primary device is the Options window, which can be accessed from Form Designer, Enter, Classic Analysis and StatCalc. Options allows the user to set values for parameters controlling language and translation, data analysis, code plug-ins, data access from web surveys and cloud capture, and general items such as the default file format and working directory.