Heterogeneity and the nonparametric analysis of consumer choice: conditions for invertibility

This paper considers structural nonparametric random utility models for continuous choice variables. It provides sufficient conditions on random preferences to yield reduced- form systems of nonparametric stochastic demand functions that allow global invertibility between demands and random utility components. Invertibility is essential for global identifcation of structural consumer demand models, for the existence of well-specified probability models of choice and for the nonparametric analysis of revealed stochastic preference

Alternative interpretations of hours information in an econometric model of labour supply

This paper examines the labour supply behaviour of married women in France. Estimating a model with tax parameter variation, careful re-examination of the treatment of the unearned income variable and taking account of education in modelling preferences result in substantially lower elasticities than found in our previous empirical analysis. It turns out that distinguishing between part-time, full-time and long hours gives virtually the same results as treating observed hours as reflecting desired hours. We provide extensive specification diagnostics, including Heckman-Andrews tests, as well as Hausman tests for the comparison of different handlings of the hours information. We also consider different assumptions concerning the perception of the impact of the tax system and provide some evidence in favour of a correct perception. --

The U.K. as a Technological Follower: Higher Education Expansion and the College Wage Premium

The proportion of U.K. people with university degrees tripled between 1993 and 2015. However, over the same period the time trend in the college wage premium has been extraordinarily flat. We show that these patterns cannot be explained by composition changes. Instead, we present a model in which firms choose between centralized and decentralized organizational forms and demonstrate that it can explain the main patterns. We also show the model has implications that differentiate it from both the exogenous skill-biased technological change model and the endogenous invention model, and that U.K. data fit with those implications. The result is a consistent picture of the transformation of the U.K. labour market in the last two decades

XMM-Newton observations of the eastern jet of SS433

The radio supernova remnant W50 hosts at its center the peculiar galactic X-ray binary SS 433. It shows a central spherical structure with two `ears' which are supposed to be formed by the interaction of the precessing jets of SS 433 with the supernova shell. In two pointings in September/October 2004 for 30 ks each the eastern jet of SS 433 was observed with XMM-Newton to study the outermost parts of the `ear' and the X-ray bright emission region about 35 arcmin from SS 433. The spectra consist of two components: a non-thermal power law with photon index \Gamma ~ 2.17+/-0.02 and a thermal component at a typical temperature of kT ~ 0.3 keV. The X-ray emission seems to fill the whole interior region of the radio remnant W50. The jet terminates in the eastern `ear' in a ring-like terminal shock which indicates a flow with a kind of hollow-cone morphology. The spatial coincidence of X-ray and radio emission suggests physical conditions similar to those found at the outer shocks of ordinary supernova remnants. The bright emission region closer to SS 433 radiates non-thermally in a spatially well confined geometry at higher X-ray energies. At soft X-rays the shape of the region gets blurred, centered on the hard lenticular emission. The shape of this region and the bend in the jet propagation direction might be caused by the interaction of a re-collimated jet with the outer, non homogeneous interstellar matter distribution. The physical conditions leading to the re-collimation of the jet and the peculiar emission morphology are far from being understood and require deeper observations as well as a detailed modeling of the interaction of a jet with its surroundings.Comment: 10 pages, 8 figures, to appear in A&

Job changes and hours changes: Understanding the path of labour supply adjustment

This paper uses British panel data to investigate single women’s labour supply changes in response to three tax and benefit policy reforms that occurred in the 1990s. These reforms changed individuals' work incentives and we use them to identify changes in labour supply. We find evidence of small hours of work effects for two of such reforms. A third reform in 1999 instead led to a significant increase in single mothers' hours of work. The mechanism by which the labour supply adjustments were made occurred largely through job changes rather than hours changes with the same employer. These results are confirmed when we look at hours changes by stated labour supply preferences. Finally, we find little overall effect of the reforms on wages

Alternative interpretations of hours information in an econometric model of labour supply

This paper examines the labour supply behaviour of married women in France. Estimating a model with tax parameter variation, careful re-examination of the treatment of the unearned income variable and taking account of education in modelling preferences result in substantially lower elasticities than found in our previous empirical analysis. It turns out that distinguishing between part-time, full-time and long hours gives virtually the same results as treating observed hours as reflecting desired hours. We provide extensive specification diagnostics, including Heckman-Andrews tests, as well as Hausman tests for the comparison of different handlings of the hours information. We also consider different assumptions concerning the perception of the impact of the tax system and provide some evidence in favour of a correct perception

Thermodynamic and magnetic properties of the layered triangular magnet NaNiO2

We report muon-spin rotation, heat capacity, magnetization, and ac magnetic susceptibility measurements of the layered spin-1/2 antiferromagnet NaNiO2. These show the onset of long-range magnetic order below T_N = 19.5K. Rapid muon depolarization persisting to about 5K above T_N is consistent with the presence of short-range magnetic order. The temperature and frequency dependence of the ac susceptibility suggests that magnetic clusters persist above 25K in the paramagnetic state and that their volume fraction decreases with increasing temperature. A frequency dependent peak in the ac magnetic susceptibility at T_sf = 3K is observed, consistent with a slowing of spin fluctuations at this temperature. A partial magnetic phase diagram is deduced.Comment: 4 pages, 4 figure

Spin freezing and dynamics in Ca_{3}Co_{2-x}Mn_{x}O_{6} (x ~ 0.95) investigated with implanted muons: disorder in the anisotropic next-nearest neighbor Ising model

We present a muon-spin relaxation investigation of the Ising chain magnet Ca_{3}Co_{2-x}Mn_{x}O_{6} (x~0.95). We find dynamic spin fluctuations persisting down to the lowest measured temperature of 1.6 K. The previously observed transition at around T ~18 K is interpreted as a subtle change in dynamics for a minority of the spins coupling to the muon that we interpret as spins locking into clusters. The dynamics of this fraction of spins freeze below a temperature T_{SF}~8 K, while a majority of spins continue to fluctuate. An explanation of the low temperature behavior is suggested in terms of the predictions of the anisotropic next-nearest-neighbor Ising model.Comment: 4 pages, 2 figure