Sample Allocation Across Condition Arms

Survey experiments need enough respondents in each condition arm to support the intended analysis. Before publishing, decide how many participants should reach each arm, whether assignment should be equal or weighted, and whether quotas should cap any cells.

1. Step 1: Calculate expected n outside the editor. Decide target completes per arm, expected screen-outs, and any unequal allocation before configuring Flow conditions.

   Step 1: Plan allocation before configuring Flow

   Block Builder

   Flow

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   Flow Canvas

   Interactive routing surface from the app, running in no-persist help mode.

   Consent and Study Intro

   1 question

   Political Knowledge Block

   2 questions

   Control Message

   1 question

   Treatment Message

   1 question

   Outcome Measures

   2 questions

   Survey Ends

   Anchors explicit end of survey

2. Step 2: Open Flow. Create or select the condition set that assigns respondents to the arms.

   Step 2: Open Flow and select condition set

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   Flow

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   Flow Canvas

   Interactive routing surface from the app, running in no-persist help mode.

   Consent and Study Intro

   1 question

   Political Knowledge Block

   2 questions

   Control Message

   1 question

   Treatment Message

   1 question

   Outcome Measures

   2 questions

   Survey Ends

   Anchors explicit end of survey

3. Step 3: Set assignment percentages. Enter equal or weighted random assignment values and confirm they total 100 percent.

   Step 3: Set assignment percentages

   Block Builder

   Flow

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   Flow Canvas

   Interactive routing surface from the app, running in no-persist help mode.

   Consent and Study Intro

   1 question

   Political Knowledge Block

   2 questions

   Control Message

   1 question

   Treatment Message

   1 question

   Outcome Measures

   2 questions

   Survey Ends

   Anchors explicit end of survey

4. Step 4: Add stratification if needed. Use a variable that appears before the split when assignment must be balanced within groups.

   Step 4: Configure stratification variable

   Block Builder: Question Name

   The export variable label is the column name for this question in downloaded data.

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   Question text

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5. Step 5: Open Deploy for quotas. Add quota targets for arms or cells when collection should stop or reroute after a count is reached.

   Step 5: Configure quotas in Deploy

   Block Builder

   Flow

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   Deploy

   Configure publishing, links, quotas, and theme from the Deploy tab.

6. Step 6: Export pilot data. Confirm condition assignments and quota-relevant fields appear in Export before launch.

   Step 6: Check condition fields in Export

   Block Builder

   Flow

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   Export

   Download analysis-ready response data from the Export tab.

In Flow, random assignment percentages determine expected allocation across arms. Equal splits are common for control and treatment comparisons. Unequal splits can be useful when one arm is more expensive, when a treatment is exploratory, or when the design intentionally oversamples a group.

Stratified assignment helps balance arms within important groups. Quotas help manage target counts after responses start. Use both carefully: stratification shapes assignment probabilities, while quotas manage whether a target cell remains open.

• Each condition set has clearly named arms.
• Assignment percentages total 100 percent.
• Stratification variables appear before the split.
• Quota targets match the planned sample allocation.
• Exports include condition assignments for analysis.

• Create Experimental Conditions
• Set Survey Quotas
• Export Research Survey Responses
• Preview and Pilot Test a Survey