Wheat variety yield data: Do commercial and public performance tests provide the same information?
研究了堪萨斯州商业和公共小麦育种项目性能测试数据中产量差异的来源，发现差异源于管理实践、农艺条件、田间位置和种子遗传特性，而非选择性偏差。
Abstract Wheat yields from reported performance test results are of economic importance to wheat producers, since their profits depend on selecting the optimal variety for their location. However, our data shows differences in absolute and relative wheat yields between commercial and public wheat breeding program's performance test data in Kansas. Newly available data are used to test if the difference in yields arose from potential selectivity bias, and to determine the contribution of private and public wheat breeding programs to varietal yield improvement during 2007–2012. Both Heckman selection models and multiple regression showed no statistical evidence of the potential presence of selectivity bias rather, managerial practices, agronomic conditions, field location, and inherent genetic traits of the seed variety were identify as the source of yield differences.