During planning a randomized trial researcher are particularly concerned that age is a prognostic variable - that is, the prognosis for the disease under consideration is much worse in older patients....

Extracted text: During planning a randomized trial researcher are particularly concerned that age is a prognostic variable - that is, the prognosis for the disease under consideration is much worse in older patients. A good solution would be to do.. (choose one best answer). factorial randomization O masked randomization O stratified randomization cross-over randomization outcome randomization