Begin a Survey With Different Conditions

A survey can begin by assigning respondents to different conditions before anyone sees a question. Add a Logic Split at the top of the Flow canvas, then connect each condition arm to its first block.

A Logic Split is a questionless routing block. Use it when assignment should happen at the start of the survey. If routing depends on an answer collected earlier, branch from the block that contains that question instead.

1. Step 1: Build each path. In Block Builder, create the first block for every condition, such as Control, Treatment A, and Treatment B.

2. Step 2: Open Flow and the Block Bank. Find Logic Split in the Block Bank.

   Step 2: Find Logic Split
3. Step 3: Drag Logic Split onto the beginning of the canvas. Place it above the first content blocks. It becomes a routing block and does not add a respondent-facing page.
4. Step 4: Choose a condition set. Use the Logic Split outgoing control to select an existing condition set or create one. Add and name every arm you need.
5. Step 5: Configure assignment. Choose weighted random assignment for experimental groups, or deterministic rules when an imported or embedded variable decides the path.
6. Step 6: Connect each arm. Drag each labeled arm to the first block respondents in that condition should see. The paths can rejoin at a shared outcomes block or continue to separate end screens.

Create a condition set with Control, Treatment A, and Treatment B. For equal random assignment, give each arm one third of the allocation. Connect the three Logic Split outputs to the three corresponding opening blocks, then connect those paths to a common outcomes block if everyone should answer the same measures afterward.

For unequal cells, planned sample sizes, and allocation checks, see Sample Allocation Across Condition Arms.

• Use a Logic Split when respondents should be assigned before answering a question, including random treatment assignment or routing based on a value already supplied with the response.
• Branch from an existing block when the path depends on an answer in that block, such as eligibility, consent, or a screening response.

Both approaches use condition sets and can create two, three, or more paths. The difference is where the routing decision occurs.

• Confirm that the Logic Split is the first reachable item in the flow.
• Make sure every condition arm connects to a block or an end screen.
• For weighted random assignment, confirm that allocations total 100 percent.
• Preview each path and verify that paths rejoin where intended.

• Create Experimental Conditions
• Branching and Skip Logic
• Troubleshoot Survey Flow