There are a number of secondary endpoints related to platelet transfusions, hemostasis, and other concerns. The four most important secondary endpoints will compare the three study arms with respect to the following outcomes: 1) platelet utilization rates (total number of platelets transfused x 10 ^11); 2) number of platelet transfusion events (frequency of transfusions); a transfusion event would be defined as each separate platelet transfusion issued by the study site's transfusion service; 3) highest category of bleeding during time of study (Platelet Dose Trial Bleeding Scale Grades less than or equal to 1, 2, 3, or 4 by arm); and 4) bleeding severity based on number of days with bleeding (total days of bleeding and bleeding/thrombocytopenic day), intensity of bleeding, and number of sites with bleeding (if such a severity score has been validated and published by the time the study is completed).