Weighting vs quota controls compares approaches that may look interchangeable but answer different questions or rely on different assumptions. The right choice depends on the decision, population, data, realism and cost of error.
Side-by-side comparison
| Dimension | Weighting | quota controls |
|---|---|---|
| Primary purpose | Adjust contribution of completed cases | Control achieved sample counts during recruitment |
| Evidence form | Weights based on design or calibration variables | Target cells by observed characteristics |
| Main strength | Corrects known imbalance and design | Prevents obvious sample imbalance |
| Main risk | Can reduce effective sample size and cannot fix all bias | Does not create random selection |
How to choose
Adjust contribution of completed cases and its assumptions fit the intended population and decision.
Control achieved sample counts during recruitment and its assumptions fit the intended population and decision.
A method used in the previous study is not automatically the right method for the next decision.
State what different outcomes will cause the organisation to do before seeing the result.
When a combined design is stronger
Many comparisons are false binaries. One method may establish structure or prevalence while another explains context, trade-offs or mechanisms. A sequential design is useful when the first stage improves the instrument, alternatives or interpretation of the second.
Common comparison mistakes
- Comparing labels while ignoring different estimands, populations or task formats.
- Assuming the method with more data is automatically more valid.
- Using cost or speed as the only selection rule.
- Combining outputs that were generated under incompatible definitions.
Selection checklist
This reference is written by Ninth Atlas as a decision-oriented explainer. It separates definition, design, analysis and limitations so a method is not mistaken for an answer. Final study specifications should be reviewed against the actual population, evidence, risk and regulatory context.