Dealing with 'Ongoing' duration in epicurves
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
Christine Roseveare Analyst Regional Public Health 570 9194 027 495 9671
Christine:
Perhaps two different legal values for the second date, eg:
01/01/1800 for missing 01/01/2050 for ongoing
then you get a negative interval for missing and too large an interval for ongoing, then in Analysis, you exclude the negatives and give a single value for all that are too large to graph the curve or perhaps better exclude them as well. If new information on BETTER comes in, it is easy to search for the value for ongoing in EpiData Entry.
...or something the like,
Hans
epidata-list@lists.umanitoba.ca 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
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.
Jamie
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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