Converts intervals in ctsem long format data to absolute time
ctDeintervalise(datalong, id = "id", dT = "dT", startoffset = 0)
data to use, in ctsem long format (attained via function ctWideToLong)
character string denoting column of data containing numeric identifier for each subject.
character string denoting column of data containing time interval preceding observations in that row.
Number of units of time to offset by when converting.