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发帖数: 53 | | z*****g
发帖数: 63 | 2 it means for the clinical trial of a certain drug or treatment, one group of
people is first used as control while the other group is used for treatment
group. After certain time, the previous control group will be further used
as treatment group, while the previous treatment group will be used as
control group, thus 2 groups of people will have equal opportunity to enter
either treatment or control group. The crossover practice will reduce the
chance of systemic error and overcome some ethical |
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