[EpiData-list] Dealing with 'Ongoing' duration in epicurves

epidata-list at lists.umanitoba.ca epidata-list at lists.umanitoba.ca
Tue Dec 2 06:31:02 CST 2008

As Hans pointed out you need to distinguish missing status from ongoing 
illness. I suggest introducing another field that will indicate status 
as ill/recovered/unknown.

To report duration of illness, replace the missing date for everyone 
whose status is "ill" with the current date, provided you are doing this 
on a regular basis. This yields the best (MLE) estimate of mean duration 
of illness.


Christine wrote:
>> I would appreciate it if those working with outbreaks could reply 
>> about how they enter and display "ongoing" duration of illness. I 
>> have been given an Excel sheet to analyse in Epidata. For this 
>> outbreak people were asked the date and time when they became unwell 
>> and the date and time when they felt better. There is a calculated 
>> field in the spreadsheet that calculates duration in days (date 
>> better - date unwell), but for some people this is empty because 
>> "ongoing" has been entered as text in the "date better" field. I want 
>> to modify the Excel sheet so I include those people with 'ongoing' 
>> illness in an epidemic curve.
>> I thought I could enter a date sometime in the future instead of 
>> 'ongoing' This would mean the duration days would not be blank, but a 
>> number of days well beyond the maximum value for those whose illness 
>> is finished. What do others do?
>> thanks
>> Christine

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