Please see these posts
or even better the original paper
Ekholm, Anders G., July 21, 2014
Components of Portfolio Variance:
R2, SelectionShare and TimingShare
Available at SSRN: http://ssrn.com/abstract=2463649
Modified http://ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js to a secure url
Modified http://d3js.org/d3.v3.min.js to a secure url
Modified http://timelyportfolio.github.io/rCharts_nvd3_tests/libraries/widgets/nvd3/js/nv.d3.min-new.js to a secure url
Modified http://nvd3.org/assets/lib/fisheye.js to a secure url
https://ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js
https://d3js.org/d3.v3.min.js
https://timelyportfolio.github.io/rCharts_nvd3_tests/libraries/widgets/nvd3/js/nv.d3.min-new.js
https://nvd3.org/assets/lib/fisheye.js