In science, a variable is something that can be changed, measured or controlled in an experiment. Scientists look at variables to understand how they affect things. A variable is any one of the things ...

Ethics committees and funding agencies often receive protocols that involve either too many or too few animals to answer the specific research question being investigated. It is evident that a greater ...

When conducting surveys, two kinds of nonresponse may cause incomplete data files: unit nonresponse (complete nonresponse) and item nonresponse (partial nonresponse). The selectivity of the unit ...

This is a preview. Log in through your library . Abstract Heterogeneity among firms has been an important issue in studying firms' technical efficiencies. If firms do not randomly fall into different ...