H-0 and odds on cosmology

Recent observations by the Hubble Space Telescope of Cepheids in the Virgo cluster imply a Hubble constant H-0 = 80 +/- 17 km s(-1) Mpc(-1); other recent observations find 70 less than or similar to H-0 less than or similar to 90 km s(-1) Mpc(-1) with several large excursions in either direction. We attempt to clarify some issues of interpretation of these results for determining the global cosmological parameters Omega and Lambda. In this paper, we use these results as a case study in the formalism of Bayesian model comparison, allowing a rigorous comparison of the different cosmological possibilities. We concentrate our analysis on three recent determinations of the Hubble constant, but the results are generic so long as they prefer H(0)t(0) greater than or similar to 1, which would seem to require Lambda > 0 within the context of Friedmann-Robertson-Walker cosmologies. With our more rigorous methods, the data do indeed suggest a universe with a nonzero cosmological constant but vanishing curvature: Omega + Lambda = 1.