Table 3. List of notations used in SGD method.

The symbols used for SGD method are shown.

Notation	Description
$\lambda \left(A,B\right)$	Weight edge between reviewers $A$ and $B$
$CRS\left(A,B,p\right)$	The co-review similarity between reviewers $A$ and $B$ while reviewing product $p$
$t_A^p$	The time when reviewer $A$ reviewed product $p$
$R_A^p$	Rating is given by reviewer $A$ on product $p$
$L\left(g\right)$	The loss function for the group $g$
$R_g$	Number of reviewers in group $g$
$P_g$	Number of products in group $g$
$L\left(r\right)$	Date of latest review by reviewer $r$
$F\left(r\right)$	Date of the first review by reviewer $r$
$V_r$	Number of reviews by reviewer $r$
${\gamma }_r^p$	Rating score is given by reviewer $r$ on product $p$
$\overline{{\gamma }_r^p}$	The average rating score of product $p$ (given by all reviewers)
${\cap }_{r\in R_g}{P}_r$	Number of common products reviewed among all the reviewers r in group $g$
${\cup }_{r\in R_g}{P}_r$	Number of total products reviewed by all the reviewers r in group $g$
$S^2\left(p,g\right)$	The variance of rating scores of the product p by reviewers in group $g$
$R_{g_p}$	Number of reviewers who reviewed the product $p$ in group $g$