Sample Allocation and Quota Calculator for Multi-Country Studies
Split a survey sample across countries, regions or segments: proportional, equal, square-root or Neyman allocation, with minimums, weights and design effect.
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How to use the sample allocation calculator
- Enter your total sample and list the cells: countries, regions, company-size bands or any other strata.
- Add each cell's population. Any unit works, because only relative sizes matter.
- Choose an allocation method and a minimum sample per cell.
- Compare the precision of each cell with the precision of the weighted total.
Which allocation method should I use?
| Method | Best for | Trade-off |
|---|---|---|
| Proportional | An accurate total (e.g. a global figure) | Small countries get tiny samples that cannot be reported alone. |
| Equal | Comparing countries or segments with each other | The weighted total is less precise because large cells are under-sampled. |
| Compromise (square root) | Reporting both cells and the total | Neither is optimal, but both are usable. The usual choice for multi-country trackers. |
| Neyman | Estimating a total or mean when variability differs between cells | Needs an estimate of each cell's standard deviation. |
The cost of disproportionate samples
When cells are sampled out of proportion, the total must be weighted back, and weighting reduces precision. Kish's design effect measures the cost: with a design effect of 1.5, 3,000 interviews give the same precision as 2,000 in a proportional sample. The calculator shows the design effect for your plan and for the alternatives, so you can choose with the numbers in front of you.
Worked example: a B2B study by company size
A software vendor wants 1,200 interviews across small, mid-size and large firms to estimate annual software spend. Large firms are few but their spend varies far more. Neyman allocation, with standard deviations of 12, 30 and 85 (in $000), gives large firms a much bigger share than their 2% of the population, which minimises the error of the total spend estimate. Press Example to load it.
Frequently asked questions
How should I split a sample between countries?
If each country will be reported on its own, give each a robust base (often 300–500) and weight for regional totals. If only the global total matters, allocate proportionally. A square-root split is a sensible middle ground.
What is a good minimum cell size?
Common floors are 100 (±10 points) for reporting a cell on its own and 50 for directional reads.
What is a quota sample?
A non-probability sample where you set targets for groups such as age, gender, region or country, and stop recruiting each group when its target is reached. This calculator sets those targets.
Need the respondents, not just the numbers?
Global Vox Populi runs quantitative and qualitative fieldwork in 170+ countries through its own proprietary panels of consumers, B2B and IT decision-makers, physicians, nurses, patients, caregivers and payers. ISO 9001, ISO 20252 and ISO/IEC 27001 certified and HIPAA compliant, following ESOMAR and Insights Association guidelines.
Check feasibilityLink to this tool
Free to use in proposals, courses and articles. If it helped, a link back is appreciated:
<a href="https://globalvoxpopuli.com/tools/sample-allocation-calculator/">Sample Allocation Calculator</a> by Global Vox Populi