*Create some sample data. set seed 1. data list free/click. begin data 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 end data. if $casenum = 1 timestamp = 0. if sysmis(timestamp) timestamp = lag(timestamp) + rv.uniform(0,120). formats timestamp(time10). exe. *Compute session count (session = 3 minutes = 180 seconds). compute session = trunc(timestamp/180) + 1. exe.