Law360, New York (December 5, 2014, 11:26 AM EST) -- The recent report and recommendation from the New York federal magistrate judge in In Re Air Cargo Shipping Services Antitrust Litigation[1] draws attention to a particular type of statistical testing that is often used in the economic analysis of class certification. The magistrate judge referred to this testing — which constitutes sensitivity analysis in economics — as "sub-regressions."[2] Generally speaking, the objective of such testing is to determine whether the purported effects derived from estimating a given regression model hold for different subgroups in the underlying data. This type of statistical testing is prevalent in economics research more generally and also in the economic analysis of class certification issues....