Modeling Credibility of Area-level Crop Insurance Under Proxy Yields with Non-Gaussian Copulas
摘要
When crop insurance programs are introduced in areas with limited historical data, premium rates are often based on proxy data from neighboring regions. This study evaluates the credibility of such proxy data in rating US county-level cotton revenue insurance contracts. We apply flexible copula-based models and value at risk to estimate target (‘true’) premiums using complete yield and price data, and simulate missing completely at random scenarios where proxy data are used to fill gaps. Premiums based on pooled proxy data from two or more adjacent counties are then compared to target rates using root mean square error and diversification effects. Results reveal substantial (−37 to +189%) distortion in proxy-based premiums across policy types, with each policy variant exhibiting a unique optimal proxy. We identify alternative risk pools and copula-specific models that improve premium accuracy by up to 50%, saving $9.8 million in subsidies in Texas alone. These findings underscore the importance of robust proxy data selection to minimize market distortions from inaccurate premiums and subsidies, and enhance the sustainability of crop insurance programs.