About the software Epi Info™ is a public domain software package designed for the global community of public health practitioners and researchers. It provides for easy form and database construction, data entry, and analysis with epidemiologic statistics, maps, and graphs. Epi Info can be downloaded from http://www.cdc.gov/epiinfo EpiData Software has developed from securing the principles of Epi Info V6 for DOS to an independent documentation oriented system. EpiData can be downloaded from http://www.epidata.dk
Conventions used in this training guide Text to be entered on screen is shown in this font.
Directions to drop-down menu items are shown in bold type, e.g. File > Save. Save
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Table of Contents
Table of Contents Acknowledgements...............................................................................i Table of Contents ..................................................................................ii Aim and Objectives ..............................................................................1 Outbreak Scenario................................................................................2 Creating a Questionnaire using EpiData.............................................3 Entering Data using EpiData ...............................................................17 Outbreak Investigation using Epi Info Analysis.................................19 Using Analysis with routine COSURV data .........................................35 Other capabilities of EpiData and Epi Info ........................................39 Appendix I – Comparison of Epi Info & EpiData ...............................44 Appendix II – Contents of course CD-ROM.......................................48 Appendix III – Further information & resources.................................49 Appendix IV – Worksheet for 2x2 table results .................................52 Appendix V – Check code example ................................................53
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Aim and Objectives
Aim and Objectives Aim of the training To provide training on the practical use of Epi Info and EpiData in communicable disease control, with particular reference to: ♦
An outbreak situation
♦
Analysis of routine Cosurv surveillance data
Objectives By the end of the training delegates will: ♦
Have an understanding of EpiData and Epi-Info for Windows and their component elements
♦
Be able to use EpiData to design a data entry form for a questionnaire in an outbreak situation
♦
Be able to use EpiData to enter outbreak investigation data into a record suitable for analysis in Epi Info for Windows
♦
Be able to use Analysis to obtain useful statistical and epidemiological information from an EpiData / Epi-Info for Windows database for outbreak investigation purposes
♦
Be able to use Analysis to import routine Cosurv surveillance data into Epi-Info for Windows, and obtain useful statistical and epidemiological information
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Outbreak Scenario
Outbreak Scenario On the 17th August, you receive a telephone call from a gentleman who reports that he and several others who attended a buffet following a funeral were suffering symptoms of food poisoning. The buffet, provided by an external caterer, was held at a local club following the funeral, and mourners arrived at the club at around 3.00 pm on 14th August. Food left over from the buffet was placed in the main bar areas of the club for club members to consume later that day. Initial activity involves obtaining of a list of people who attended the funeral and others who may have eaten the food provided for the funeral buffet. A list of food served at the buffet has been obtained from the caterer, and cross-referenced with initial information gathered from cases. Indications are that around 70-80 people attended the funeral, and approximately 40-50 of these people may have experienced symptoms consistent with food poisoning. Table 1 - List of foods served at the buffet sausage rolls
chicken rolls
salmon sandwiches
pickled onions
ham sandwiches
egg rolls
corned beef sandwiches
ham rolls
egg sandwiches
chicken nuggets
chicken sandwiches
cheese & biscuits
crisps
gateaux
pasties
An Outbreak Control Team has been convened, and has decided to undertake a cohort study to investigate the outbreak. The OCT assigns you with the following tasks: ♦
Establish the case definition
♦
Develop a structured questionnaire to investigate the outbreak.
♦
Enter questionnaire data into an appropriate computer database
♦
Analyse the data to describe outbreak and identify exposures associated with illness
This training uses this scenario to introduce the various functions of EpiData and Epi Info for Windows, and their particular use in outbreak investigation.
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Creating a Questionnaire using EpiData
Creating a Questionnaire using EpiData Basic Questionnaire Creation A screenshot of the main EpiData screen is shown.
We want to create a new questionnaire, so select Define Data > New .QES File (It is also possible to edit an existing questionnaire, by using Define Data > Open .QES File). File This creates an empty text file into which we can enter information. On creation of the file, the following toolbar option also becomes available. Clicking this button brings up the ‘Field pick list’ dialog. This dialog makes it easy to create different kinds of fields. As an example, we will create one or two of the basic field types in our questionnaire.
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Creating a Questionnaire using EpiData
First, type an appropriate heading into the first line of your questionnaire, such as “Lead Officer Training March 2007”. Then, on the row below, enter Surname: Leave the cursor flashing after the colon. If the Field pick list is not already showing, click the button to bring it on screen. Select the ‘Text’ tab from the pick list. This then gives a short option list of ‘text’, ‘upper-case text’, and ‘encryption field’. For now we’ll accept the default ‘text’ option. Set the field length to 20, then click the Insert button. EpiData inserts a series of underscore characters after the Surname: label. Underscore characters _ are how EpiData denotes plain text fields. The number of underscores indicates the maximum length of the field. On the next line, type Forename: Using the field pick list again, insert another text field of 15 characters. Now let’s try a different field type – dates. On the next line, type Date of birth: Select the ‘Date’ tab from the field pick list. This presents two lists of options – general date fields on the left, and ‘automatic’ dates on the right. General date fields are formatted in three different ways. For most of us in Europe, the