What Is It? A new approach to matching methods for causal inference simultaneously maximizes both balance (similarity between treated and control groups) and matched sample size. Existing approaches often force researchers to fix one variable, leading to suboptimal solutions or manual iteration.
The Matching Frontier Concept The paper introduces the 'matching frontier,' which represents all possible matching solutions with maximum balance for different sample sizes. This allows researchers to select optimal matches in a single step rather than through iterative tweaking.
Fast Algorithms Researchers derive fast algorithms that calculate this frontier for several commonly used balance metrics, making complex methods more accessible and efficient.
Applications Demonstrated The approach is demonstrated using analyses of the effect of sex on judging effectiveness (in judging programs) and job training outcomes. These examples show how researchers can extract new knowledge from existing datasets by achieving better balance without sacrificing sample size or vice versa unnecessarily.
Key Findings & Implications By eliminating manual iteration, this method streamlines causal inference analysis while maintaining all substantive detail.
| The Balance-Sample Size Frontier in Matching Methods for Causal Inference was authored by Gary King, Christopher Lucas and Richard Nielsen. It was published by Wiley in AJPS in 2017. |
