Breaks and Trends in OECD Countries’ Energy-GDP Ratios

This paper uses the econometrics of endogenous structural breaks to examine changes in energy intensity for OECD countries over 1960-2009. Nearly all OECD countries currently have significant negatively trending energy-GDP ratios; but for several countries those negative trends are recent, and two countries have recent significant positive trends. For several countries, energy intensity had a significant positive trend followed by a break and then a significant negative trend. Those break-dates, however, appear to have little to do with level of development (GDP per capita). Instead, among the likely causes of break timing are the volatile energy prices of the 1970s and early 1980s and the increased concern for the environment in the late 1960s and early 1970s. These findings have implications for future modeling of energy consumption as well as for the role of energy price policy in developed and developing countries.energy intensity, endogenous structural breaks, modeling environment and development, Resource /Energy Economics and Policy, Q43, O13,

Information criteria for astrophysical model selection

Model selection is the problem of distinguishing competing models, perhaps featuring different numbers of parameters. The statistics literature contains two distinct sets of tools, those based on information theory such as the Akaike Information Criterion (AIC), and those on Bayesian inference such as the Bayesian evidence and Bayesian Information Criterion (BIC). The Deviance Information Criterion combines ideas from both heritages; it is readily computed from Monte Carlo posterior samples and, unlike the AIC and BIC, allows for parameter degeneracy. I describe the properties of the information criteria, and as an example compute them from WMAP3 data for several cosmological models. I find that at present the information theory and Bayesian approaches give significantly different conclusions from that data.Comment: 5 pages, no figures. Update to match version accepted by MNRAS Letters. Extra references, minor changes to discussion, no change to conclusion

Demographic dynamics and per capita environmental impact: using panel regressions and household decompositions to examine population and transport

Demographic variables have tended to be ignored in many environment-development analyses. This paper examines how population changes (in aging, households, and urbanization/density) can help explain changes/differences in personal transport using both macro- and micro- level data. First, panel regressions are performed with IEA-OECD road sector energy use data (spanning 1960-2000) on spatial population measures, average household size, and age structure data. Then US household data is used to determine the extent compositional changes in the nature of households can explain changes in per capita driving. An Environmental Kuznets Curve for per capita road energy use was rejected—the coefficients on the GDP squared terms were insignificant and the implied turning points were well outside the sample range; instead, the relationship between wealth and road energy was found to be monotonic (log-linear). The ideas that more densely populated countries have less personal transport demands, the young drive more, and smaller households mean higher per capita driving were confirmed. The basic result from the household decompositions was that changes in demand were more important than compositional changes, however, during some periods the compositional change component was considerable. A few policy implications can be drawn from these analyses. First, the look at micro data implies that there is much potential for policy to affect transport behavior since the compositional component of change—more difficult for policy to alter—is smaller than the behavioral or demand component. However, the look at the macro data implies that spatial factors, like population density and urbanization—which also can be difficult to alter—are significant in influencing personal transport demand.OECD countries, energy consumption, environmental policy, household size, transport

Viable inflationary models ending with a first-order phase transition

We investigate the parameter space of hybrid inflation models where inflation terminates via a first-order phase transition causing nucleation of bubbles. Such models experience a tension from the need to ensure nearly scale invariant density perturbations, while avoiding a near scale-invariant bubble size distribution which would conflict observations. We perform an exact analysis of the different regimes of the models, where the energy density of the inflaton field ranges from being negligible as compared to the vacuum energy to providing most of the energy for inflation. Despite recent microwave anisotropy results favouring a spectral index less than one, we find that there are still viable models that end with bubble production and can match all available observations. As a by-product of our analysis, we also provide an up-to-date assessment of the viable parameter space of Linde's original second-order hybrid model across its full parameter range.Comment: 9 pages, 7 figures. Revised version: corrections to description of the historical development of the models. v3: Minor corrections to match version accepted by PR

The Brussels deal to save the Euro confounded its Anglo-Saxon doubters. The British press once again underestimated how integrated Europe really is.

Treaty change looms as the Eurozone edges closer towards greater fiscal union. Roger Liddle looks at what this might mean for the future of the European Union and Britain’s place within it.