  We present the effect of yttrium substitution on superconductivity in the
La$_{1-\textit{x}}$Y$_{\textit{x}}$O$_{0.5}$F$_{0.5}$BiS$_{2}$ system.
Polycrystalline samples with nominal Y concentrations up to 40% were
synthesized and characterized via electrical resistivity, magnetic
susceptibility, and specific heat measurements. Y substitution reduces the
lattice parameter \textit{a} and unit cell volume \textit{V}, and a correlation
between the lattice parameter \textit{c}, the La-O-La bond angle, and the
superconducting critical temperature $T_c$ is observed. The chemical pressure
induced by Y substitution for La produces neither the high-$T_c$
superconducting phase nor the structural phase transition seen in
LaO$_{0.5}$F$_{0.5}$BiS$_{2}$ under externally applied pressure.
