  Let $\beta>1$ be a real number. In this paper, the Hausdorff dimension of
sets consisting of pairs of numbers with prescribed quantitative waiting time
indicators in $\beta$-expansions are determined. More precisely, let $I$ be the
unit interval $[0,1)$ and write $\underline{R}^\beta(x,y)$ and
$\overline{R}^\beta(x,y)$ as the lower and upper quantitative waiting time
indicators of $y$ by $x$ in $\beta$-expansions, respectively. Define the
waiting set on the plane by \[E_\beta(a,b)=\left\{(x,y)\in
I^2\colon\underline{R}^\beta(x,y)=a,\overline{R}^\beta(x,y)=b\right\}.\] where
$0\leq a\leq b\leq\infty$, then the set $E_\beta(a,b)$ is always of Hausdorff
dimension two for any pair of numbers $a$ and $b$. In addition, some
generalizations for this result are also given in the last section.
