Quantitative Study of Geometrical Scaling in Deep Inelastic Scattering at HERA

We propose a method to assess the quality of geometrical scaling in Deep Inelastic Scattering and apply it to the combined HERA data on $\gamma^{\ast}p$ cross-section. Using two different approaches based on Bjorken $x$ binning and binning in $\gamma^{\ast}p$ scattering energy $W$, we show that geometrical scaling in variable $\tau\sim Q^{2} x^{\lambda}$ works well up to Bjorken $x$'s 0.1. The corresponding value of exponent $\lambda$ is 0.32 -- 0.34.