TeX source:

\text { Variance } \%=\beta_{1} \frac{\operatorname{cov}\left[\log \left(\bar{t}_{i j}^{k}\right), \log \left(\overline{\operatorname{Logistlcs}_{i j}}\right)\right]}{\operatorname{var}\left[\log \left(\bar{t}_{i j}^{k}\right)\right]}