Published online by Cambridge University Press: 20 November 2018
For an analytic function $f$ on the unit disk $\mathbb{D}$, we show that the ${{L}^{2}}$ integral mean of $f$ on $\text{c}\,\text{}\,\text{ }\!\!|\!\!\text{ z }\!\!|\!\!\text{ }\,\text{}\,\text{r}$ with respect to the weighted area measure ${{\left( 1\,-\,|z{{|}^{2}} \right)}^{\alpha }}dA\left( z \right)$ is a logarithmically convex function of $r$ on $\left( c,\,1 \right)$, where $-3\,\le \,\alpha \,\le \,0\,\text{and}\,\text{c}\,\in \,[\,0,\,1)$. Moreover, the range $[-3,\,0]$ for $\alpha $ is best possible. When $c\,=\,0$, our arguments here also simplify the proof for several results we obtained in earlier papers.