Use of Computers in Data Analysis and Presentation in Epidemiology

1. Why Computers Are Indispensable in Epidemiology

• Speed and accuracy - Large datasets can be processed in seconds with minimal human error
• Storage capacity - Thousands of records (patient data, surveillance reports, laboratory results) stored and retrieved instantly
• Reproducibility - Analyses can be repeated, shared, and validated
• Multitasking - Simultaneous data entry, analysis, report generation, and communication
• Complex modelling - Disease spread models, risk calculations, and predictive analytics that are impossible manually

2. Applications of Computers in Epidemiological Data Analysis

A. Data Collection and Entry

• Electronic questionnaires - Digital forms replace paper surveys, reducing transcription errors
• Electronic Health Records (EHRs) - Patient data queried directly for surveillance
• Syndromic surveillance systems (e.g., ESSENCE in the US) - Real-time monitoring of emergency department visits and symptom patterns
• Mobile data collection - Tablet/smartphone-based field surveys during outbreak investigations

B. Data Management and Cleaning

• Database management systems - Microsoft Access, MySQL, REDCap for organizing surveillance data
• Spreadsheet software - Microsoft Excel, Google Sheets for basic storage and manipulation
• Error checking - Duplicate detection, range validation, missing value handling

C. Statistical Analysis

• Descriptive statistics (frequencies, proportions, means, medians)
• Measures of association (relative risk, odds ratio, attributable risk)
• Hypothesis testing (chi-square, Fisher's exact test, t-test)
• Survival analysis (Kaplan-Meier curves)
• Regression analysis (logistic, linear, Poisson)
• Cluster analysis and case detection

D. Data Presentation and Visualization

• Tables - Frequency distributions, cross-tabulations, case listings
• Graphs - Bar charts, pie charts, histograms, scatter plots, line graphs (epidemic curves)
• Maps - Geographic Information Systems (GIS) for spatial analysis of disease distribution
• Dashboards - Interactive visual displays of surveillance data in real time
• Word processing - Formal reports with bold headings, embedded tables, charts - produced in Microsoft Word or similar

E. Disease Surveillance and Reporting

• Automated alerts for notifiable disease thresholds
• Linkage between laboratory, clinical, and demographic data
• Real-time outbreak monitoring
• Data sharing between local, national, and international public health agencies (WHO, CDC)

F. Geographic Information Systems (GIS)

G. Modelling and Simulation

• Mathematical models of disease spread (SIR models)
• AI and machine learning for predictive epidemiology
• Computer simulation of intervention effects

3. Epi Info - Dedicated Public Health Software

Background

Main Uses

• Outbreak investigations
• Developing small to mid-sized disease surveillance systems
• Analysis, visualization, and reporting for larger systems
• Teaching epidemiology and public health analytic methods at schools of public health worldwide

Core Modules

1. Form Designer

• Rapidly creates electronic questionnaires and data entry forms
• Drag-and-drop placement of questions on multiple pages
• Supports data types: text, numbers, dates, times, Boolean (Yes/No)
• Drop-down lists, code tables, and comment legal fields
• Check Code feature: programs intelligent logic into forms (e.g., skip patterns - if age < 18, skip a question; if a field is left blank, display a warning)
• Handles all database management tasks (table creation, key management, relationships) automatically

2. Enter

• Customized data entry interface based on forms created in Form Designer
• Validates data during entry using check code rules
• Reduces entry errors in real time

3. Analysis (Classic Analysis)

• Full-featured statistical analysis module
• Commands include: FREQ, MEANS, TABLES, LIST, MATCH, GRAPH, MAP, LOGISTIC
• Calculates:
  • Frequencies and cross-tabulations
  • Chi-square tests, Fisher's exact test
  • Odds ratios and relative risks with 95% confidence intervals
  • Attack rates and epidemic curves
  • Logistic regression
• Generates tables and graphs for reports
• Programmable using a command language - analyses can be saved and re-run

4. Visual Dashboard

• Lighter-weight, user-friendly analysis interface
• Produces visual summaries - charts, tables, and graphs - without needing command knowledge
• Good for non-technical users and routine reporting

5. Maps Module

• Displays data by geographic reference or GPS coordinates
• Generates choropleth maps, dot maps, and cluster maps
• Integrates spatial data with disease surveillance records
• Supports Shapefiles for custom geographic boundaries

6. StatCalc

• Built-in statistical calculator (works pre- and post-data collection)
• Calculates:
  • Sample size for surveys and case-control studies
  • Chi-square and Fisher's exact test from 2x2 tables
  • Odds ratios and relative risks
  • Confidence intervals
  • Population-based statistics (age standardization, etc.)
• Available on desktop and Android app
• Extremely useful during field investigations before data are fully collected

7. Other Utilities

• Web Survey - Deploys questionnaires online for remote data collection
• Companion for Android - Mobile data collection in the field
• Data Packager - Packages data for secure transfer between field teams and central offices
• Nutritional Anthropometry - Calculates z-scores and nutritional indices (weight-for-age, height-for-age) for nutrition surveys
• Check Code - Conditional logic for data validation

Key Advantages of Epi Info

• Free of cost (public domain, CDC-funded)
• No IT expertise required for basic use
• Specifically designed for outbreak investigations and field epidemiology
• Works on limited-resource settings (no internet needed for basic functions)
• Produces immediate results - useful during active outbreaks
• Multilingual (translations available)
• Compatible with large databases via SQL Server for multi-user applications

4. Other Common Software Tools in Epidemiology and Public Health

5. Summary