Step-up simultaneous tests for identifying active effects in orthogonal saturated designs

A sequence of null hypotheses regarding the number of negligible effects (zero effects) in orthogonal saturated designs is formulated. Two step-up simultaneous testing procedures are proposed to identify active effects (nonzero effects) under the commonly used assumption of effect sparsity. It is shown that each procedure controls the experimentwise error rate at a given $\alpha$ level in the strong sense.Comment: Published at http://dx.doi.org/10.1214/009053606000001136 in the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Foreign Workers and the Organic Farms’ Demand for Seasonal Unskilled Labor

This study analyzes farm labor management strategies of organic farms by employing Heckan selection model. Econometric results present interesting relationships between foreign worker-related variables and the hiring of non-family seasonal part-time workers. First, the extent of hiring is inversely related to the population of illegal residents. Second, the outcome variable (extent of hiring) is directly related to the number of H2A permits (foreign guest farm worker visas for temporary, contractual work) issued. The results also indicate that higher wages, corporate farms, and more educated, younger and full-time farm operators are associated with greater tendencies to hire non-family seasonal part-time workers. Family labor is used to supplement the lack of available non-family seasonal part-time workers.organic farm, unskilled labor, immigration, Heckman selection model, foreign worker, Farm Management,