17,772 research outputs found
Testing the suitability of polynomial models in errors-in-variables problems
A low-degree polynomial model for a response curve is used commonly in
practice. It generally incorporates a linear or quadratic function of the
covariate. In this paper we suggest methods for testing the goodness of fit of
a general polynomial model when there are errors in the covariates. There, the
true covariates are not directly observed, and conventional bootstrap methods
for testing are not applicable. We develop a new approach, in which
deconvolution methods are used to estimate the distribution of the covariates
under the null hypothesis, and a ``wild'' or moment-matching bootstrap argument
is employed to estimate the distribution of the experimental errors (distinct
from the distribution of the errors in covariates). Most of our attention is
directed at the case where the distribution of the errors in covariates is
known, although we also discuss methods for estimation and testing when the
covariate error distribution is estimated. No assumptions are made about the
distribution of experimental error, and, in particular, we depart substantially
from conventional parametric models for errors-in-variables problems.Comment: Published in at http://dx.doi.org/10.1214/009053607000000361 the
Annals of Statistics (http://www.imstat.org/aos/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Executive Pay in the Public Sector: The Case of CEOs in UK Universities
We analyse top management public sector pay using a panel data of university Vice Chancellors (VC) in UK. We assess how institutional performance, hierarchical effects, and personal characteristics determine VC pay. VC personal data covers personal details, qualifications and career history, which let us distinguish between internal promotions and hires from outside academia. We use the results of three Research Assessment Exercises as academic performance indicators, and university financial positions as measures of sound executive management. We analysed the importance of university salary structure and how they affect VC pay. Fixed and random institutional effects are also identified and analysed.pay, public sector, CEO, universities
Constraining Scatter in the Stellar Mass--Halo Mass Relation for Haloes Less Massive than the Milky Way
Most galaxies are hosted by massive, invisible dark matter haloes, yet little
is known about the scatter in the stellar mass--halo mass relation for galaxies
with host halo masses . Using mock catalogues based
on dark matter simulations, we find that two observable signatures are
sensitive to scatter in the stellar mass--halo mass relation even at these mass
scales; i.e., conditional stellar mass functions and velocity distribution
functions for neighbouring galaxies. We compute these observables for 179,373
galaxies in the Sloan Digital Sky Survey (SDSS) with stellar masses and redshifts 0.01 0.307. We then compare to mock
observations generated from the dark matter
simulation for stellar mass--halo mass scatters ranging from 0 to 0.6 dex. The
observed results are consistent with simulated results for most values of
scatter (0.6 dex), and SDSS statistics are insufficient to provide firm
constraints. However, this method could provide much tighter constraints on
stellar mass--halo mass scatter in the future if applied to larger data sets,
especially the anticipated Dark Energy Spectroscopic Instrument Bright Galaxy
Survey. Constraining the value of scatter could have important implications for
galaxy formation and evolution.Comment: 11 pages, 1 table, 9 main body figures, 9 appendix figure
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