... August 2011 Lauridsen and Pradhan Health Economics Review 2011, 1:11 http://www.healtheconomicsreview.com/content/1/1/11 References World Health Organisation: The World Health Report 2000: Health ... quintiles and 2, and quintiles 3, 4, and were grouped together This produced a binary variable labelled ‘poor economic status’, Lauridsen and Pradhan Health Economics Review 2011, 1:11 http://www.healtheconomicsreview.com/content/1/1/11 ... weighted covariance of yi and Ri, i.e C= 2 cov w (yi , Ri ) = μ Nμ N wi (yi − μ)(Ri − i=1 ) Lauridsen and Pradhan Health Economics Review 2011, 1:11 http://www.healtheconomicsreview.com/content/1/1/11...