It uses a statistical technique known as instrumental variable analysis to execute the strategy. (newamericaneconomy.org)
To account for differences between the two groups that were not known, such as surgeon, institutional experience, and patient's functional status, we implemented a set of instrumental variable analyses. (bmj.com)
We also use a new instrumental variable, short - run fluctuations in the demand for schooling, to predict private schooling. (papers.ssrn.com)