# Estimates of External Validity Bias When Impact Evaluations Select Sites Nonrandomly

> Research article (Educational Evaluation and Policy Analysis, 2016) · cited 40× · AI/ML

**Wikidata**: [openalex:W2319036384](https://www.wikidata.org/wiki/openalex:W2319036384)  
**Source**: https://4ort.xyz/entity/estimates-of-external-validity-bias-when-impact-evaluations-select-sites-nonrandomly