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Minimization: A new method of assigning patients to treatment and control groups
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1974
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Family MedicinePatient SelectionTreatment EffectOptimal Experimental DesignQuasi-experimentTreatment Plan EvaluationTreatment DevelopmentClinical TrialsRandomized Controlled TrialClinical OutcomesBiostatisticsClinical EfficacyStatisticsHealth Services ResearchNew MethodHealth SciencesControl GroupsAcceptable Experimental DesignClinical Trial ManagementClinical Trial AnalysisOutcomes ResearchComputer SimulationsSevere ImbalancePatient SafetyTreatment PlanningPersonalized TreatmentPatient ManagementMedicineClinical Trial EvaluationClinical Trial Design
The study proposes a new minimization method for assigning patients to treatment and control groups that reduces differences in both group size and patient characteristics. The method assigns patients to groups by iteratively balancing multiple patient characteristics to minimize overall group imbalance. Computer simulations with 40 patients and 15 variables show that minimization reduces the probability of severe imbalance by four‑ to fivefold compared to randomization, matches blocking for a single variable, and is less susceptible to experimenter bias, supporting its replacement of randomization in clinical trials.
This paper describes a new method of assigning patients to treatment and control groups to minimize differences between the groups, not only in the number of patients but in patient characteristics. Testing the method by computer simulations, using data on 40 patients with 15 variates each, demonstrates a four‐ to fivefold reduction of the probability of severe imbalance, relative to randomization. Minimization can maintain tight control of one variate, comparable to the currently acceptable experimental design of blocking, while reduCing the probability of severe imbalance in the other 14 variates by a factor of 3. It also compares favorably with accepted methods regarding susceptibility to experimenter bias. Therefore, it is suggested that minimization should replace randomization in assigning patients in clinical trials.