Glossary · Reliability, calibration, and statistics
Kish effective sample sizen_eff
n_eff = (Σ w_i)² / Σ w_i²: the number of equally weighted items that carry the same information as a weighted sample. A collapse of n_eff relative to n signals a suite that badly mismatches the target population.
Also called: effective sample size
Defined in
Handbook · ValidationEstimands, pass rates, and intervalsWrite the estimand first, then report n, an honest interval and the right functional, from Wilson to pass^k to reweighted estimates.Related terms
- Stratified estimate
- A pass rate combined from per-stratum estimates with the target population's weights, Σ w_h p̂_h. It lets a suite over-sample informative slices and still report the deployment mix.
Where it comes up
- Task distributions and dataset engineeringHandbook · Claim
- Notation and formula cardHandbook · Reference