  We have composed a sample of 68 massive stars in our galaxy whose projected
rotational velocity, effective temperature and gravity are available from
high-precision spectroscopic measurements. The additional seven observed
variables considered here are their surface nitrogen abundance, rotational
frequency, magnetic field strength, and the amplitude and frequency of their
dominant acoustic and gravity mode of oscillation. Multiple linear regression
to estimate the nitrogen abundance combined with principal components analysis,
after addressing the incomplete and truncated nature of the data, reveals that
the effective temperature and the frequency of the dominant acoustic
oscillation mode are the only two significant predictors for the nitrogen
abundance, while the projected rotational velocity and the rotational frequency
have no predictive power. The dominant gravity mode and the magnetic field
strength are correlated with the effective temperature but have no predictive
power for the nitrogen abundance. Our findings are completely based on
observations and their proper statistical treatment and call for a new strategy
in evaluating the outcome of stellar evolution computations.
