In this equation, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hat \sigma _Y^2{\mathrm{/}}n$$\end{document}σ^Y2∕n is not necessarily known but can be estimated using the equation analogous to (6) for βl7\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathrm{se}}^2\left( {\hat \beta _l} \right) = \frac{{\hat \sigma _Y^2(1 - R_l^2)}}{{n\,\hat \sigma _l^2}}$$\end{document}se2β^l=σ^Y2(1-Rl2)nσ^l2
