Frequency of binaries divided by two times the fraction of binaries with q > 0.5 expected for the cases of Fisher et al. (2005) mass-ratio distribution (upper panel) and from the distribution obtained by randomly extracting secondary stars from a Kroupa (2002) IMF (bottom panels). Red points with the error bars are the mean values of the observed binary frequency normalized by two times and have been already plotted in Fig. 25. The slope of the best-fitting least-squares gray straight lines and the reduced-χ² obtained from the comparison of the observed and theoretical distribution are quoted in the figure.