Constant Sum Survey Questions

Ask respondents to allocate a fixed budget of points across items for budget, tradeoff, and importance-weighting research.

When To Use Constant Sum

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.

Block Builder: Constant Sum

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.

How It Supports Research Design

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.
Initial item order and shading: reduce list-position bias in long item sets.

Configure It In Domandata

Step 1: Open Block Builder. Open the survey and select the block where the allocation task belongs.
Step 1: Open Block Builder
Step 2: Add a Constant Sum question. Choose Constant Sum from the question type selector.
Step 2: Choose Constant Sum question type
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
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
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
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

Preview: Try Constant Sum

Constant Sum: Respondent View

Allocate points across items so the total matches the budget — the same interface respondents see.

Data And Export Notes

Each item exports as its own column with the exact number of points the respondent allocated to it. The respondent interface shows a live running total and flags when it doesn't match the budget, but submission is not blocked on an exact match. Add a data-quality check that flags rows where the per-respondent sum is off-budget before analysis.

Constant sum data is compositional — each respondent's row sums to (approximately) the same budget. Some analyses require log-ratio or other compositional-data transforms rather than treating each item as an independent continuous variable.

Related Help

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