  We select ~20000 metal-rich star-forming galaxies from the SDSS-DR2 to study
the R23-P method suggested by Pilyugin et al. for metallicity estimates. The
oxygen abundances derived from their revised R23-P method are ~0.19 dex lower
than those derived from the previous one, and ~0.60 dex lower than the Bayesian
abundances obtained by the MPA/JHU group. These abundance discrepancies
strongly correlate with the P parameter and weakly depend on the log(R23)
parameter.
