Annu. Rev. Astron. Astrophys. 1980. 18: 165-218 Copyright © 1980 by Annual Reviews. All rights reserved

1.2. Strategies of Measuring Source Structure

There are two complementary strategies for obtaining basic information about radio sources from measurements of structure. One can extrapolate conclusions drawn from detailed measurements of individual source morphologies to the whole population of radio sources, or one can try to infer properties of radio sources from statistical analyses of well-defined samples. Highly detailed measurements can only be made for a typical source, e.g. the closest (Cygnus A, Virgo A, Centaurus A) or the largest (3C236, DA 240, NGC 315, NGC 6251). On the other hand, the statistical approach limits the range of properties one can investigate. And even when samples are chosen with the greatest of care, selection effects that are difficult to take into account often remain.