Price flexibility in British supermarkets

This paper delivers a significantly different empirical perspective on micro pricing behaviour and its impact on macroeconomic processes than previous studies. We examine a seven year period of pricing behaviour by the major British supermarkets encompassing the recession year 2008 and the partial recovery of 2009. Several of our findings run strongly counter to established empirical regularities, in particular the high overall frequency of regular or reference price changes we uncover, the greater intensity of change in more turbulent times and the numerical dominance of price falls over rises. The pricing behaviour revealed also significantly challenges the implicit assumption that prices are tracking cost changes

Identifying and characterising price leadership in British supermarkets

Price leadership is a concept that lacks precision. We propose a deliberately narrow, falsifiable, definition and illustrate its feasibility using the two leading British supermarket chains. We find both firms engaging in leadership behaviour over a range of products, with the larger being somewhat more dominant but the smaller increasing leadership activity over time. Surprisingly, more price leadership events are price reductions than price increases, but the increases are of larger monetary amounts (so average price increases over time) and the events appear not necessarily related to cost changes. Price leadership appears to play some role in price increases

Pricing in inflationary times- the penny drops

We investigate micro pricing behaviour in groceries (the UK’s most important consumer market) over eight years including the inflationary period of early 2008. We find behaviour sharply distinguished from most previous work, namely that overall basket prices rise but more individual prices fall than rise! This is consistent with retailers obscuring the fact of rising basket prices. We employ a significant new source of data that captures cross-competitor interplay in prices at a very detailed level. Unusually but importantly, our work takes into account that consumers buy baskets of goods, rather than individual products, when shopping at supermarkets.

Containing big soda: Countering inducements to buy large-size sugary drinks

Health concerns about overconsumption of large portions apply to a wide range of highly calorific foods and drinks. Yet, amongst all products, sugar-sweetened soft drinks and especially sugared soda are the ones which seem to raise the most ire because they contain little or no nutritional value beyond their sugar content and because of the way that vendors encourage excessive consumption by pricing jumbo-size portions to look like bargains while making smaller portions appear overpriced. This paper considers the logic of such extreme value size pricing and reveals why this marketing practice can harm economic welfare beyond public health concerns. The paper shows why policy interventions, including portion cap rules and soda taxes, seeking to reduce portion sizes and curb the consumption of large-size sugary drinks might fail when they do not fully take into account or appreciate the strategic responses that vendors might adopt to retain value size pricing

Grain Physics and Rosseland Mean Opacities

Tables of mean opacities are often used to compute the transfer of radiation in a variety of astrophysical simulations from stellar evolution models to proto-planetary disks. Often tables, such as Ferguson et al. (2005), are computed with a predetermined set of physical assumptions that may or may not be valid for a specific application. This paper explores the effects of several assumptions of grain physics on the Rosseland mean opacity in an oxygen rich environment. We find that changing the distribution of grain sizes, either the power-law exponent or the shape of the distribution, has a marginal effect on the total mean opacity. We also explore the difference in the mean opacity between solid homogenous grains and grains that are porous or conglomorations of several species. Changing the amount of grain opacity included in the mean by assuming a grain-to-gas ratio significantly affects the mean opacity, but in a predictable way.Comment: 19 pages, 6 figures, accepted for publication in Ap

Identifying and characterising price leadership in British supermarkets

Price leadership is a concept that lacks precision. We propose a deliberately narrow, falsifiable, definition then develop it, illustrate its feasibility and test it using the two leading British supermarket chains. We find both firms engaging in leading prices upward over a range of products, with the larger being initially more dominant but the smaller increasing leadership activity to take overall leadership over time. However, more price leadership events are price reductions than price increases, consistently led by the smaller firm. Nevertheless, the increases are of larger monetary amounts than the falls, so average basket price increases over time

Pricing in inflationary times: The penny drops

How does the frequency and magnitude of micro-price rises and falls relate to macroeconomic crisis, as well as moderation? Weekly micropricing behaviour in British groceries was investigated across three leading retailers over the moderation period 2004–7 and the crisis period 2008–10. We find significant price flexibility sharply distinguished from behaviour observed in most previous works. Downward price flexibility increased markedly in 2008. Overall basket prices rise, but significantly more individual prices fall than rise in the latter period. Tests of obfuscation in price setting suggested that large numbers of small price falls were used to disguise the basket price rises

The Chemical Composition and Gas-to-Dust Mass Ratio of Nearby Interstellar Matter

Recent results on nearby interstellar gas and interstellar byproducts within the solar system are used to select among the equilibrium radiative transfer models of the nearest interstellar material of Slavin and Frisch (2002). Assuming O/H~400 ppm, Models 2 and 8 are found to yield good fits to available data on local interstellar material, and pickup ions and anomalous cosmic rays inside of the heliosphere, with the exception of Ne. For these models, the density of interstellar gas at the entry point to the heliosphere is n(HI)~0.20 /cc and n(e-)~0.1 /cc. These models suggest the chemical composition of the nearby ISM is ~60--70% subsolar if S is undepleted (where HI and HII must be included for abundance calculations). Gas-to-dust mass ratios of 178-183 for solar abundances, or 611-657 for 70% solar abundances are found. The percentage of the dust mass that is carried by iron is directly correlated with the gas-to-dust mass ratio implying an Fe-rich grain core remains after grain destruction.Comment: 36 pages, 6 figures, accepted by Ap

Historical Reconstruction Reveals Recovery in Hawaiian Coral Reefs

Coral reef ecosystems are declining worldwide, yet regional differences in the trajectories, timing and extent of degradation highlight the need for in-depth regional case studies to understand the factors that contribute to either ecosystem sustainability or decline. We reconstructed social-ecological interactions in Hawaiian coral reef environments over 700 years using detailed datasets on ecological conditions, proximate anthropogenic stressor regimes and social change. Here we report previously undetected recovery periods in Hawaiian coral reefs, including a historical recovery in the MHI (∼AD 1400–1820) and an ongoing recovery in the NWHI (∼AD 1950–2009+). These recovery periods appear to be attributed to a complex set of changes in underlying social systems, which served to release reefs from direct anthropogenic stressor regimes. Recovery at the ecosystem level is associated with reductions in stressors over long time periods (decades+) and large spatial scales (>103 km2). Our results challenge conventional assumptions and reported findings that human impacts to ecosystems are cumulative and lead only to long-term trajectories of environmental decline. In contrast, recovery periods reveal that human societies have interacted sustainably with coral reef environments over long time periods, and that degraded ecosystems may still retain the adaptive capacity and resilience to recover from human impacts