Number of standard deviations $n_{\sigma}$ of the modeled correlation function for a given set of scattering parameters (effective range $d_0$ and scattering length $f_0$) with respect to the data, together with various model calculations \cite{ND, NF, NSC89, NSC97, ESC08, Ehime1, Ehime2, fss1, fss2, FG, HKMYY} and measurements \cite{Adamczyk:2014vca}. The gray shaded area corresponds to the region where the Lednick\'{y} model predicts a negative correlation function for \pp collisions at $\sqrt{s} = 7\,$TeV.