Ratio of the matter power spectra P(k) of different f(R) models, including neutrinos of different mass, with respect to ΛCDM. The different f(R) models, labelled as f₄(R), f₅(R), and f₆(R), are described in the text. f₆(R) with any neutrino mass and f₅(R) with m_ν = 0.15 eV all have a matter power spectrum within 10% of the ΛCDM one. In the following we illustrate how different statistics can be used (or not) to discriminate these models, showing complete results in particular for f₅(R) for illustration.