<qa>  How many patients are the desired study size?Study size 200 trauma patients with mortality as outcome and all patients that survived during the same time period. Mortality within 30 days is assumed to be 15 , based on past studies. Thus, 1350 patients is the desired study size. The estimated time needed to collect the desired data is two months four project officers, one per hospital. A project officer collect data from the first ten patients per shift, 5 days per week. Thus, a data collector collect data from 50 patients per week and from 200 patients per month. The total collected data per month will then be from 800 patients. Two months of collected data will be from 1600 patients. Consequently, it will take about two months to reach the desired study size. 