How to calculate how much time a participant has spent on a page

You can to calculate the time spent on a certain page with the help of the relative time stamp:

• (cont.)Internal variable name: dt_send_pag_000n ()

• External variable name: rts_000n For pgid > 99999: ts_000n

• Description: relative timestamp for page xxxx

 Example: rtsxxxx1 = 6 and rtsxxxx2 = 27, i. the subject was on the page for 21 seconds.