Constant Sum Survey Questions

Constant sum questions ask respondents to divide a fixed budget of points across a set of items. They are useful for budget allocation studies, resource-tradeoff experiments, importance weighting, time-use estimates, and any measure where the relative magnitude between items matters, not just which item is picked or how they rank.

Use constant sum when the size of the tradeoff is the data. If you only need the order of preference, use Ranking instead; if you need a single choice, use Multiple Choice.

• Item list: the set of things respondents allocate points across.
• Total points: the fixed budget respondents must divide (e.g. 100 points).
• Minimum and maximum per item: bound how much (or how little) a respondent can put on any single item.
• Decimal allocations: allow fractional points when whole numbers are too coarse.
• Instructions: an optional box shown above the question, for directions such as "Divide 100 points to show how important each item is to you." It is translatable like the question text.
• Initial item order and shading: reduce list-position bias in long item sets.
• Random subset of items: show each respondent a random subset of the items instead of the full list, useful when the full list is too long to allocate across comfortably.
• Input control: Number (a numeric field per item, the default) or Slider. In slider mode, Show endpoint numbers labels each slider's minimum and maximum, and Allow typing a value adds a number box beside each slider for exact entry.
• Over-budget behavior (slider only): Clamp stops a dragged handle at whatever value keeps the total exactly at budget, leaving every other item untouched. Auto-Balance instead pulls the difference back out of the other items, proportional to their own headroom above their minimum. Neither approach is established in the literature as producing better data — Qualtrics clamps, Sawtooth auto-balances, and no published comparison says which is preferable, so pick whichever behavior your pretest respondents find less confusing.
• Variable cost per item: optional. When turned on, each item gets its own cost per unit and the budget caps total spend (units × cost, summed) rather than the raw unit count — useful for a task like "allocate your $100 across these products" where each product has a different real-world price.

1. Step 1: Open Block Builder. Open the survey and select the block where the allocation task belongs.

   Step 1: Open Block Builder

2. Step 2: Add a Constant Sum question. Choose Constant Sum from the question type selector.

   Step 2: Choose Constant Sum question type

3. Step 3: List the items. Add every item respondents will allocate points across. Keep the list short enough that respondents can compare items without scrolling back and forth.

   Step 3: List the items

4. Step 4: Set the point budget and bounds. Choose the total (100 points is conventional), then set a minimum and, if needed, a maximum per item so no single item can absorb the whole budget.

   Step 4: Set the point budget

5. Step 5: Name and code it. Add a readable variable name so each item's exported column is easy to identify later.

   Step 5: Variable Name

6. Step 6: Preview the allocation. Confirm the running total updates as points are entered and that the interface clearly shows how many points remain.

   Step 6: Preview the allocation

Each item exports as its own column with the exact number of units the respondent allocated to it (or, for a weighted question, the raw unit count — multiply by that item's cost yourself if you need spend per item). The respondent interface shows a live running total and flags when it doesn't match the budget. For a required question, submission is blocked until the total is within budget; for an optional question it is not, so an off-budget row can still reach your data.

Response Quality automatically flags a completed-looking response whose total lands off budget ("Unbalanced Allocation"), an allocation split exactly evenly across every item or dumped entirely onto one item (a low-severity "Straightlining" flag — an even split can genuinely reflect indifference, not just inattention, so treat it as a signal to look closer rather than an automatic exclusion), and a response completed implausibly fast for its item count ("Speeding"). Instrument Review separately flags an authored minimum or maximum per item that makes the budget mathematically unreachable, and nudges when an item list runs long enough that dividing a budget across it gets meaningfully harder to reason about.

• Ranking Survey Questions for order-only preference data
• MaxDiff Survey Questions for best-worst tradeoffs across many items
• Survey Variable Names and Recodes
• Export Research Survey Responses