Overview of EpiInfo 6

Dr. Troy Gepte

Why do we use Statistical Software?

• Convenience

• Accuracy

• Guides data collection

• Ensures that data is processed

• Facilitates the use of coding

EpiInfo 6

• A Word Processing, Database and Statistical Software Package for Public Health and Epidemiology

• This suite of programs was developed jointly by the Centers for Disease Control and the World Health Organization for field investigations into public health.

• Freeware

EpiInfo 6

• Can be downloaded from www.cdc.gov in three diskettes (1 disk per file)

• Most recent version is EpiInfo 6.04d (January 2001) – for faster computers; this version fixed the bugs in the previous versions

• Runs on DOS and Windows• Requires about 10 MB of memory• Not compatible with 64-bit Windows operating

systems.

Screen Shots of EpiInfo 6

• Main Menu

• EPED – Word Processor

• ENTER – Database Program

• ANALYSIS – Statistical Program

What can we do with it?

• Construct databases

• Enter and manage data

• Analyze data

• Make graphs and maps

Basic Entry and Analytical Principles

• GIGO

• Reap what you sow

• One can drown in data

• After data collection and entry, what was it really that I wanted to do in the first place?

Programs within EpiInfo 6

• EPED: the EPidemiologic text EDitor • ENTER: for data entry • ANALYSIS: for statistical analysis and reporting • IMPORT: for importing data files from other

database programs • EXPORT: for exporting data to other database

and statistical programs • STATCALC: a statistical calculator • EPITABLE: an alternative statistical calculator

Data Entry

• Questionnaire Files:– Before creating a data file in Epi Info, you must

first create a questionnaire (QES) file. – This QES files will serve as the template for your

data entry screen and data base. – QES files can be created with any ASCII text

editor, such as Epi Info's text editor (EPED) or Windows NOTEPAD.

– However, they must always end with the file extension .QES.

Data Entry (cont)

• Regardless of what editor program you use to create QES files, these files should contain:– (1) Survey questions and instructions

(2) Variable names(3) Variable indicator codes

• Survey questions and instructions should be brief, clear, non-leading, and unambiguous. 

• Variable names must start with a letter and can contain no more than 10 characters.

• Your variable names should be descriptive and, to avoid confusion, should be enclosed in {curley brackets}.

Data Entry (cont)

• Variable indicator codes define the type and length of the variable being created. The most common variable indicator codes are:

• Indicator Code Data Type# Numeric integer#.# Numeric real___ Alphanumeric<A> Alphanumeric, upper case only<Y> "Yes / no" (binary)<mm/dd/yyyy> Date, American<dd/mm/yyyy>  Date, European

Data Management

• Record Files:– QES files are used to create REC files, which in turn, are

used to store data. To create an empty REC file:1. Start the ENTER program from the Programs menu

2. Type the name of the REC file you want to create into the first field on the screen

3. Press the Tab key to get to the next field

4. Select option 2 to create a new data file

5. Enter the name of the QES file which will form the basis of the REC file

6. Press the Tab key

7. Type "Y"

Data Management (cont)

• A REC file that looks like the QES file used to create it will now appear on screen.

• Data are entered into the blank fields on this screen by the user. • After entering each record, the user types Y to store the data

permanently.• Function-keys are used to navigate existing REC files. • A function-key menu appears on the bottom the data entry

screen. – The <Ctrl-F> key-combination is used to find a particular record– <F6> is used to delete a record– <F7> travels up one record (think "7 up")– <F8> travels down one record– <F10> quits the ENTER program

Data Management (cont)

• Researchers often need to share data with colleagues using database and statistical programs other than Epi Info.

• Since most of these data programs use proprietary file formats, a minor obstacle is encountered when trying to exchange data among different programs.

• Fortunately, Epi Info has data translators (EXPORT and IMPORT) to assist in getting around this potential obstacle.

Data Management (cont)

• To exchange data between software programs, find a file format that is common to both programs (dBASE (DBF) or Lotus worksheet (WKS) file-formats)

Summarizing dataand

Obtaining Inference from statistical tests

EpiInfo ANALYSIS Program

• Epi Info's ANALYSIS program is used to manage, print, summarize, and analyze data.

• After starting ANALYSIS from the Programs menu, your computer screen will be divided into an Output Window (above) and Command Window (below).

• A Status Line showing the name of the active data set and free memory appears above the Output Window, and a Function Key Menu is below the Command Window.

EpiInfo ANALYSIS (cont)

• ANALYSIS, itself, is command driven. There are commands for: – file processing (e.g. READ)– output control (e.g. ROUTE output to screen vs. printer)– variable manipulation (e.g. SELECT)– statistical analysis (e.g. FREQ, MEANS, TABLES).

• A list of commands is assessed by pressing <F2>. • Commands are either typed at the command prompt

(EPI6>) or sent to the command line by highlighting them from the <F2> menu and pressing Enter.

Things to do in Epi6

• Computing for means, medians and modes

• Using range and standard deviations• Constructing tables:

– Frequency distributions– Cross-tabulations

• Making graphs and maps• Performing statistical tests

Inferential statistics

Inferential statistics

• Choosing the appropriate test statistic and epidemiologic measure of association (risk ratio/odds ratio)

• Computing for:– p-value – 95% confidence interval

• Interpreting the result of the test for significance

Workshop

1. The class is free to work in groups.2. Each group will work on one case study.3. Read through the case study and follow

instructions.4. Use EpiInfo 6 to analyze the dataset used in the

case study.5. Divide the work of who will be doing:

a. descriptive assessment of the data; and,b. further analysis and/or statistical tests.

6. Answer the questions in the case study.7. Present to the class in plenary..

EpiInfo ANALYSIS

• Workshop Exercises: 1. OSWEGO.REC

2. CALUMPIT.REC

3. JAIL2.REC

Results of Analysis

Findings Results/Remarks

Age Distribution

Sex Distribution

How many got ill?

Results of Analysis

Findings Results/Remarks

Risk Factors for Illness

Recommendations

Review

Reviewing Epi6

• Review Questions:1. What program is used to create QES files?

2. What functions do QES files serve?

3. What program is used to create REC files?

4. What function do REC files serve?

5. Describe DOS file naming conventions.

6. Describe Epi Info variable naming conventions.

• Review Questions:7. How does Epi Info assign variable names?

8. What type of Epi Info variables are used to store numeric data?

9. What type of Epi Info variables can be used to store categorical (qualitative) data?

10. What Epi Info programs can open (i.e., work with) REC files?

• Answers:– 1. EPED or any other ASCII text editor.

2. QES files structure data entry screens and REC files.3. ENTER4. They store data.5. DOS files use 8 character filenames and three letter extensions. The extension identifies the file's type.6. Epi Info variable names must begin with a letter and may be no more than 10 characters in length.7. Unless the variable name is identified within {curly brackets}, Epi Info will take the 10 characters preceding a variable indicator as the variable's name.8. Numeric integer (#) and numeric real (#.#).9. Text (_), upper case text (<A>), or numeric (#) if data are numerically encoded (e.g., 1 = male, 2 = female).10. ENTER, ANALYSIS, and EXPORT

Thank you