a The data for polariton blueshifts acquired for 4% (blue) and 10% (red) samples plotted as a function of threshold pump power. Blue and red solid curves represent numerical simulations of time-integrated blueshifts, respectively. The error bars are within the marker size and correspond to standard deviations of the best-fit results of the peak energies. b The blueshift ∆E versus exciton fraction for 4% (blue) and 10% (red) samples, solid curves show the best-fit results according to Eq. (8). Error bars in b correspond to standard deviations of the blueshift (y-axis) and exciton fraction (x-axis) determined for each binning range.