By clicking the links below, you are leaving CLEAR and are subject to the privacy and security policies of the owners/sponsors of the external site. CLEAR does not control or guarantee the accuracy, relevance, timeliness, or completeness of information contained in a linked site. We also do not endorse the organizations or individuals maintaining sites that we link to, any views they express, or any products/services they offer.
The original publication can be found at: https://cepa.stanford.edu/sites/default/files/bettinger_baker_030711.pdf
If this link no longer works, you can try a Google search for the citation.