"I would appreciate it if those working with outbreaks could reply about how they enter and display "ongoing" duration of illness." We create a graph showing at what time (date) the symptoms start and graph this according to exposure or time window.

For epicurve the standard way of thinking is: ..............dayonset (start) ................................. ...... dayonset (start) ..................................... command could be: epicurve case dayonset

In a different instance we would like to analyse "pattern of disease development" or pattern of how long time disease lasts begin ----------------------- end begin ----------------------------------------- (still under observation)

The typical analysis here could be a Survival curve indicating length of disease period: Assume we have cases and string variables for start and end in the analysis. We would : read ourdata (or read from clipboard since these are copied from a spreadsheet). * generate two date variables for start and end of period: gen d stop = . if end <> "ongoing" then stop = date(end, "%dmy") gen d start = date(begin, "%dmy") * generate a case variable indicating if people were cured or are still under observation: gen i well = 0 if end <> "ongoing" then well = 1

* now we are ready for the analysis. notice the /mt which will assume that everyone with end time missing were observed until the latest of those where "stop" was "non-missing". lifetable well start stop /mt

* an alternative would be to give the stop as a precise value: e.g. Dec 1st 2008 if end = "ongoing" then stop = dmy(1,12,2008) lifetable well start stop

Notice that we did not change the "well" to 1 since keeping this with the value 0 indicates this observation was observed until given stop date, but did not develop disease.

The lifetable would show median survival, possibly grouped or compared to a reference with the options "/by=sex /p25 ....."

Regards Jens Lauritsen EpiData Association