Estimation of σ₈ and n_s at z = 4 for parameter values (two dashed black lines) different from the parameter values with which the IMNN has been trained (dashed blue, red, and green lines). The black curves show the PDF of the estimated parameter values (at two different values). Each realization in the distribution of the estimated parameters is a bootstrap realization of a sample size of 50 mock spectra over the entire testing set. The distributions of the parameters were generated with 10 000 bootstrap realizations for each parameter.