In order to guarantee the similarity of each treatment group, the "minimization" method attempts are made, which is more direct than random permuted block within strats. In the minimization method, samples in each stratum are assigned to treatment groups based on the sum of samples in each treatment group, which makes the number of subjects keep balance among the group.<ref name=":0" /> If the sums for multiple treatment groups are the same, simple randomization would be conducted to assign the treatment. In practice, the minimization method needs to follow a daily record of treatment assignments by prognostic factors, which can be done effectively by using a set of index cards to record. The minimization method effectively avoids imbalance among groups but involves less random process than block randomization because the random process is only conducted when the treatment sums are the same. A feasible solution is to apply an additional random list which makes the treatment groups with a smaller sum of marginal totals possess a higher chance (e.g.¾) while other treatments have a lower chance(e.g.¼ ).<ref name=":1">{{Cite journal|last=Pocock|first=S. J.|date=March 1979|title=Allocation of Patients to Treatment in Clinical Trials|journal=Biometrics|volume=35|issue=1|pages=183–197|doi=10.2307/2529944|jstor=2529944|pmid=497334|issn=0006-341X}}</ref>
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为了保证每个处理组的相似性,尝试了“最小化”方法,这比分层内的随机排列块更直接。在最小化方法中,根据每个处理组中的样本总和将每个层中的样本分配到处理组中,这使得受试者数量在组间保持平衡。<ref name=":0" /> 如果多个治疗组的总和相同,则将进行简单的随机化以分配治疗。在实践中,最小化方法需要根据预后因素(prognostic factors)跟踪治疗分配的每日记录,这可以通过使用一组索引卡进行记录来有效完成。最小化方法有效地避免了组间不平衡,但比块随机化涉及的随机过程更少,因为随机过程仅在治疗的总人数相同时进行。一个可行的解决方案是应用额外的随机列表,这使得具有较小边际总数的总和的治疗组具有更高的机会(例如 ¾),而其他治疗具有较低的机会(例如 ¼)。<ref name=":1">{{Cite journal|last=Pocock|first=S. J.|date=March 1979|title=Allocation of Patients to Treatment in Clinical Trials|journal=Biometrics|volume=35|issue=1|pages=183–197|doi=10.2307/2529944|jstor=2529944|pmid=497334|issn=0006-341X}}</ref>