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Table 2 Considerations in selecting a randomization and allocation strategy

From: Rapid, easy, and cheap randomization: prospective evaluation in a study cohort

Method Best setting Cost Advantages Disadvantages
Web-based randomization Multisite High - High reliability 24 h per day -Dependent on Internet functionality
- Capacity to handle large volume of randomization requests - Requires access to a device (usually a computer) to access the Internet
- Electronic audit trail created - Requires familiarity with process
  - High cost
Telephone accessible central coordinating site Multisite High - High reliability 24 h per day - Dependent on access to a working telephone
- Additional resources associated with a staffed coordinating site - Requires staffing of central coordinating site
- Audit trail created - High cost
Third party prepared sealed packages of identical appearance Single site, multisite possible Moderate - High reliability 24 h per day - Research Assistant or enrolling clinician must know where to find packages consistently
- Little time required to obtain participant allocation when implemented optimally - Vulnerable to breach of allocation sequence
  - Important to ensure treatment assignment cannot be discerned from package features (size, weight)
  - Preparation time/cost
Text message/email method described in this paper Single site, multisite not evaluated Low - High reliability demonstrated in a small cohort - Requires both Research Assistant and Randomization Coordinator to have functional smart phone on person with cellular network connectivity
- Allocation details received quickly - Requires Research Assistant to have functional device that can access study email account via Wi-Fi or cellular network
- Email audit trail created - Method performance during unsociable hours not yet assessed
- Low cost  
Sequentially numbered, opaque sealed envelopes Single site Low - High reliability - Research Assistant must be able to access envelopes consistently
- Allocation details received quickly - Vulnerable to breach of allocation sequence
- Audit trail created (allocation paper) - Participant personal information transferred to allocation paper
- Low cost  
Coin toss Single site Low - Easily accessible - Only simple randomization (no blocking)
- Low cost - No audit trail
     - Vulnerable to corruption