  We study a sample of Narrow-line Seyfert 1 galaxies (NLS1) in their optical
and radio features, in order to understand the differences between their radio
silent, radio-loud and radio-quiet subclasses. We first show that the different
redshift and mass distributions of radio-loud and -quiet NLS1s could be
ascribed to observational biases. We then present a geometrical model according
to which most of the different observational features of radio-loud and
radio-quiet NLS1s are ascribed to the orientation of an intrinsically
structured jet. We estimate the fraction of intrinsically jetted sources among
NLS1s that justifies the observed radio-detected population. Noticeably, under
the assumptions of the geometrical model, we derive a fraction of jetted
sources significantly larger than in standard AGN.
