<prompt> Randomization is useful to eliminateObserver biasConfounding factorsPatient biasSampling bias  <response>: Randomization: The groups should be alike with regard to ceain variables or characteristics that might affect the outcome of experiments The entire study population can be stratified into subgroups according to the variable Individuals within each subgroup can then be randomly allocated into study and control groups Ref: 25th edition, Parks Textbook of Preventive and Social Medicine, Page no. 90 