Statistical Software in Medical Research

Dr R Rejikumar  

Common Statistical Software
Epi Info

EPI Info – Version 3.5
Series of micro computer programs for handling epidemiological data (word processor/d Base in questionnaire format.
Processing and Analysis of data (features of SAS, SPSS)
Jointly developed by CDC/WHO (Turbo Pascal)
There are three levels of facilities for processing the structured data.

The first level (simplest one).

  • Running the main menu.
  • Typing or creating the questionnaire with EPED.
  • Entering the data through ENTER program.
  • Analyzing the data using Analysis program to produce lists, frequencies, cross tables etc.

Second Level of EPI Info 

  • Additional features to shape the data entry like building internal checks ,automatic coding, skip patterns, (CHECK program).
  • Selecting Records, Creating new variables, recoding of the variables (Analysis Program)
  • Carry out conditional operations with IF statements.
  • Incorporate the operators into program files so that they can be used repeatedly
  • Import file from other system like SAS,ASCII (IMPORT Program).
  • Export file from EPI INFO system to other systems like SAS,SPSS,ASCII (text) (EXPORT Program)

Third Level of EPI Info 

  • Linking two files analysis mode
  • suppose there are two files to be linked File1and File2
  • (Open file1 by Typing Read File1 in the analysis mode)
  • Type Relate Id file2 ( Id is unique identification key having the common Identifier in both files)
  • Enter data in more than one files with ENTER Program.
  • Compare duplicate files entered by different operators to detect entry operators. (VALIDATE Program)

Requirements for loading EPI Info 

  • IBM Compatible Micro Computer with PC-DOS or MS-DOS OS (version 2.0 or higher)
  • 512 K bytes of RAM.
  • At least one floppy disc drive
  • A graphics adapter to produce graphs.
  • An IBM Compatible printer
  • ** For large data , a hard disc drive of 640 KB RAM

Steps for Installing EPI Info 

  • Download the latest version of software from the website.
  • Alternatively you can click on the icon Epiinfo3 in the CD package given to you.
  • Select the Destination Drive and proceed with installation.

Running the EPI Info 

  • Click on the shortcut icon
  • Click on Enter Data
  • Select the data file.
  • Start entering data

Creating  questionnaires from EPED Editor

Run EPED from EPI Menu
Press <F2> for the file menu and create a new file (max of 8 character) with the extension “.qes” Press <F9>

If the file already exists, it will be displayed on the screen for editing.

When a questionnaire is being developed, it is necessary to tell the program variable names and type  of data fields to accept the values.

Field Types in EPI Info (EPED)

Text or general purpose  __ (* Any printable character can be entered Maximum length 80 Characters) 

  • Upper Case Text                               <A>
  • (entries will be converted to upper case)
  • Numeric                                                             #
  • (only numbers or spaces will be accepted)##.#
  • (max length 14 numbers)
  • Yes/No field                                         <Y>
  • Only Y,N and space or <enter>
  • Field Types contd..
  • Entering data through the ENTER Program
  • Run enter from the main menu
  • In response to the request for “data file”,type the name of the questionnaire “.qes”
  • Type the name of your data file (.rec)
  • Fill in the fields in the questionnaire
  • Repeat the same for all fields till the form is completed.
  • The message “write data to disk ? Y/N will appear at the bottom of the screen
  • Answer “Y” or “y”
  • Repeat the same process for several records. Press <f10>

Check : For filtration of data while data entry

Run the CHECK program from the EPI menu.

Enter the name of the record file. Type “Y”

Types of the checks :
(i) Range Checks (Min/Max): For lower range enter a value in the field and press  <f1>. Similarly for upper range enter the values and press <f2> and for adding  exceptional value press <f6>. Values other than  the specified values will not be entered .

(ii) Conditional Jumps <f7> : To set up cond. Jumps enter a value in the field and   and press <f7> . You will be asked the destination field for jump. Put the cursor  in that field and again press <f7>.

(iii) Listing of Fields and Automatic Coding <f5> and <f8>

Links two fields called DISEASE and DISEASECODE. Place the cursor in the first field  and press <f5> and then move the cursor to the field to be linked and press <f5>.Once the fields are  linked, then enter a value in the DISEASE like “Hep A” and press <f8>. The cursor will jump to field DISEASECODE ,the linked field. Suppose, say 10 and press <f8>. The Cursor will again jump back to DISEASE. Repeat this process till codes are exhausted .


  • Run ANALYSIS program from the main menu.
  • Read data file name (.rec).
  • List * (to produce list of records in the file).
  • Freq Var (will count freq for specified variable).
  • Tables V1 V2 will result in count of two fields at the same time.
  • Charts and Graphs –  Histogram, PIE, BAR, Scatter produce the specified graphs.
  • Route command  will direct the results to file by name of your choice. (result.txt)
  • <f5> command route printer or route screen
  • Analysis Cont.
  • Means var1 var2/n    will produce means    of variable var1 by var2 and produce no frequency
  • Recode         we can decode the         variable
    • (1=“ Male, 2=     “female”)
  • Sort  <var1> <var2>   Allows us to sort the      records in the specified sequence.


Relative processing time for 2,000 records
Comparison of Epi INFO
The Data entry package is very easy as  compared to other packages as the record files (.rec) of the EPI appears similar to the subject information sheet .

  • There is a provision for data entry  to be done in two or more  files related to each other ( Reg. And Follow up) records.
  • The dBase files can be read directly .No need to import them.
  • Compares duplicates files entered by different operators to detect data  entry errors.
  • The package is made by WHO and CDC is not copyrighted and free of cost.
  • Making copies for others is permitted and encouraged

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