Have lubridate subtraction return only a numeric value

Question

I have one variable called Started which is the date on which human subjects enrolled in a study and another variable called dos1 which is the date

Answer 1

You could try using difftime instead, ie:

difftime(syrrupan$Started,syrrupan$dos1,units="days")

Note that this will give you an object of class difftime, if you want a numeric vector, wrap an as.numeric around it. Note also that you can't choose months as an option for units, but you should really stick with a time unit that has a fixed length.