Observational tests of world models.

Observational aspects of the standard Friedmann-Lemaitre-Robertson-Walker cosmological model in its most popular hot-big-bang version are examined in a review of recent investigations. Topics addressed include experimental geometry, the necessity of space curvature, line lengths and areas on a sphere of constant curvature, the count-redshift relation, the redshift-magnitude equation, the predicted Hubble diagrams without and with luminosity evolution, predicted and observed count-magnitude relations, and local and high-redshift tests of the m(z) Hubble diagram. Consideration is given to nongeometrical evidence for evolution in the look-back time, the angular diameter of rigid rods, and time-scale tests. Extensive diagrams and graphs are provided.