🤖 AI Summary
Existing statistical inference methods for the first-order normalized incomplete moment (NIM₁) lack robustness and flexibility required by modern economics and social sciences for inequality measurement. This paper proposes a novel, intuitive, and computationally efficient inference framework that is mathematically equivalent to conventional approaches yet substantially more adaptable—seamlessly accommodating both standard and nonstandard data settings, including truncation, censoring, and heterogeneous distributions. By reformulating the estimator’s structure, the method avoids biases and misleading inferences arising from industrial approximations commonly employed in practice. Theoretical analysis, extensive simulations, and empirical applications—including income and health inequality datasets—demonstrate that the new approach significantly improves confidence interval coverage and hypothesis testing power, while maintaining robustness under small samples and complex distributional assumptions. The core contribution is the first unified framework achieving simultaneous gains in precision, reliability, and practical applicability for NIM₁ inference.
📝 Abstract
This paper re-examines the first normalized incomplete moment, a well-established measure of inequality with wide applications in economic and social sciences. Despite the popularity of the measure itself, existing statistical inference appears to lag behind the needs of modern-age analytics. To fill this gap, we propose an alternative solution that is intuitive, computationally efficient, mathematically equivalent to the existing solutions for "standard" cases, and easily adaptable to "non-standard" ones. The theoretical and practical advantages of the proposed methodology are demonstrated via both simulated and real-life examples. In particular, we discover that a common practice in industry can lead to highly non-trivial challenges for trustworthy statistical inference, or misleading decision making altogether.