Page Comparison

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The standard options include:

• Basic randomization
• Blocked randomization
• Blocked randomization with Stratification

Basic Randomization: (eg: CHOP Weight Loss, Way to Walk)

• This type of randomization procedure divides participants equally across groups regardless of individual characteristics. This process would create equal group sizes.
• Basic randomization and Weightedcan be accomplished by altering information contained in the settings section for each arm of your particular study
• Basic randomization should only be used if you have a medium to large “n” and if you know all participants will be randomized in a short period of time (less than 2 months)

Blocked Randomization (ex: CHF EMPOWER)

• This procedure ensures close balance of participants in each group at any time during the study enrollment period. 
• For studies will a small “n”, you are advised to use smaller block sizes (e.g. 2 and 4 for a study with 5 arms and 35 per arm). For larger studies you are advised to use larger block sizes (e.g. 4 and 8 for a study with 2 arms and 250 per arm).
• Blocked randomization should be used in most circumstances and is preferred in order to keep randomization balanced over time. If your anticipated sample size is small or you anticipate a long recruitment period you should use blocked randomization or your population may be confounded by circumstances that change over time (long recruitment period) or ending up not being evenly enrolled amongst all arms (small number in each arm).

Blocked Randomization with Stratification (ex: CMMI HeartStrong)

• In this randomization type participants will be placed in intervention arms on the basis of one or more chosen criteria (e.g., gender, BMI, age) and then randomized according to set block sizes. Participants will be divided equally across all interventions while controlling for the chosen criteria so that there is an equal number of participants with each characteristic in each intervention arm. For example, if you want to use gender as a stratification variable this would result in an equal number of woman and men across all intervention arms.
• On the randomization screen select "Block Randomization With Stratification" and click the "Update Configuration" button.
• Once this has been done a new link will appear in the Study Configuration navigation titled "Configure Strata"
• Clicking on this link will take you to a page where the Strata groups that your study will use can be configured. To create a strata click on the "New" button at the top of the page. When creating a strata there are two parameters that can be set are "name" and "block sizes." The name parameter is used across the site as a way to differentiate different strata from each other. The block sizes parameter determines what the potential block sizes? are potential block sizes are for that strata.
• On the main strata configuration page each strata for a study is displayed as well as the total number of participants that have been randomized into each arm in the current randomization block, the totals for all blocks, and the potential block sizes for each strata.
• Once all the needed strata have been created the feedback tool can be used to configure how participants are placed in strata. Any encounter during enrollment can be used to assign a participant into a strata. [NL2] 

Blocked Randomization (ex: CHF EMPOWER)

Blocked Randomization with Stratification (ex: CMMI HeartStrong)

• In this randomization type participants will be placed in intervention arms on the basis of one or more chosen criteria (e.g., gender, BMI, age) and then randomized according to set block sizes. Participants will be divided equally across all interventions while controlling for the chosen criteria so that there is an equal number of participants with each characteristic in each intervention arm. For example, if you want to use gender as a stratification variable this would result in an equal number of woman and men across all intervention arms.

Basic Randomization: (eg: CHOP Weight Loss, Way to Walk)

• This type of randomization procedure divides participants equally across groups regardless of individual characteristics. This process would create equal group sizes.

• Basic randomization can be accomplished by altering information contained in the settings section for each arm of your particular study
• Basic randomization should only be used if you have a medium to large “n” and if you know all participants will be randomized in a short period of time (less than 2 months)

Arm Weights:

• All types of randomization procedures can have weights assigned to each arm.
• By default each arm has a weight of 1. Since all arms have the same weight This process would allow there to be arms of different sizes.the arm weights are irrelevant and randomization will happen as expected for the selected randomization option.
• Once an arm has been assigned a weight, all other arms will default to a weight of 0 unless manually assigned. If an arm has  weight of 0 no participants will be randomized in to that arm.
• To effectively use arm weights you must have arms of different sizes. 
• Example: a two arm, 150 participant study consisting of a control arm and an incentive arm
  • If we want a larger control group than incentive we could set the following arm weights:
    • Control arm: 2
    • Incentive arm: 1
  • Since the control arm has twice the weight of the incentive arm participants are twice as likely to end up in that arm than the incentive arm. In order to maintain proper randomization we would need the control arm to be twice as large as the incentive arm.
    • Arm caps:
      • Control arm: 100 participants
      • Incentive arm: 50 participants

Understanding Caps:

• In WTH you will have to select the size of each of your arms.  However, it is important to set the cap of each arm a bit higher so that study staff will continue to remain blinded to which arm each participant is being randomized as full enrollment is approaching and up until the last participant is enrolled.  Close attention should be paid to when you are approaching full enrollment so that enrollment can be ceased as soon as you’ve reached your enrollment goal.

Testing Randomization before study launch:[NL4]

• The most effective way to ensure randomization is working as you would expect is to enroll a reasonable number of participants and observe what arms they are assigned to. 

WTH role permissions and access to randomization details:

• WTH Admins can see the current state of the blocks. 
• WTH Coordinators can’t see current state of the blocks so they will remain blinded to how the blocks are being filled

Other kinds of randomization:

Adaptive Randomization example: Way to Quit

• Under this randomization procedure the probability of being randomized into one of the treatment arms will adjust based on the number of participants who accept that intervention. This is a way to examine a programs’ comparative acceptance without undermining our ability to study efficacy. The probabilities of being placed into each intervention arm can be updated either on time basis (e.g., every 24 hours) or after a certain amount of participants have enrolled and accepted interventions (e.g., after every 5 participants).

• After the research team has decided how probabilities should update contact your P’unk Avenue representative to configure[NL5] . Research coordinators will be responsible for setting up the remainder of this process.

• Information contained in the settings section for each arm of your particular study will need to be adjusted based on the parameters of your study.

Cluster Randomization

• A cluster randomized trial is a trial in which individuals are randomized in groups (i.e. the group is randomized, not the individual). For example, in a study examining eating habits in high schools, we might randomize whole school to a particular intervention, rather than individual students.