Evaluating the provision of school performance information for school choice

One of the key components of any school choice system is the information given to parents as the basis for choice. We develop and implement a framework for determining the optimal performance metrics to help parents choose a school. This approach combines the three major critiques of the usefulness of performance tables into a natural, implementable metric. The best content for school performance tables is the statistic that best answers the question: “In which feasible choice school will a particular child achieve the highest exam score?” We implement this approach for 500,000 students in England for a range of performance measures. Using performance tables is strongly better than choosing at random: a child who attends the highest ex ante performing school within their choice set will ex post do better than the average outcome in their choice set twice as often as they will do worse.school choice, performance tables

More Reliable Inference for Segregation Indices

The most widely used measure of segregation is the dissimilarity index, D. It is now well understood that this measure also reflects randomness in the allocation of individuals to units; that is, it measures deviations from evenness not deviations from randomness. This leads to potentially large values of the segregation index when unit sizes and/or minority proportions are small, even if there is no underlying systematic segregation. Our response to this is to produce an adjustment to the index, based on an underlying statistical model. We specify the assignment problem in a very general way, with differences in conditional assignment probabilities underlying the resulting segregation. From this we derive a likelihood ratio test for the presence of any systematic segregation and a bootstrap bias adjustment to the dissimilarity index. We further develop the asymptotic distribution theory for testing hypotheses concerning the magnitude of the segregation index and show that use of bootstrap methods can improve the size and power properties of test procedures considerably. We illustrate these methods by comparing dissimilarity indices across school districts in England to measure social segregation.segregation, dissimilarity index, bootstrap methods, hypothesis testing

The early impact of Brighton and Hove's school admission reforms

We analyse the initial impact of a major school admission reform in Brighton and Hove. The new system incorporated a lottery for oversubscribed places and new catchment areas. We examine the post-reform changes in school composition. We locate the major winners and losers in terms of the quality of school attended. We match similar cities and conduct a difference-in-difference analysis of the policy change. We see no significant change in student sorting: if anything, the point estimates suggest a rise in socio-economic segregation. We do see a significant weakening of the dependence of school attended on student’s prior attainment.school lottery, segregation, school admissions reforms

Representing the Process of Machine Tool Calibration in First-order Logic

Machine tool calibration requires a wide range of measurement techniques that can be carried out in many different sequences. Planning a machine tool calibration is typically performed by a subject expert with a great understanding of International standards and industrial best-practice guides. However, it is often the case that the planned sequence of measurements is not the optimal. Therefore, in an attempt to improve the process, intelligent computing methods can be designed for plan suggestion. As a starting point, this paper presents a way of converting expert knowledge into first-order logic that can be expressed in the PROLOG language. It then shows how queries can be executed against the logic to construct a knowledge-base of all the different measurements that can be performed during machine tool calibration

Choosing secondary school by moving house: school quality and the formation of neighbourhoods

This paper uses the pupil census in England to explore how family house moves contribute to school and residential segregation. We track the moves of a single cohort as it approaches the secondary school admission age. We also combine a number of cohorts and estimate a dynamic nonlinear model for house moving with unobserved effects. These approaches yield the same result: moving is significantly negatively correlated with school quality, and segregation does increase as a cohort reaches age 11. However, this relationship is weak: the increase in segregation is slight and quantitative significance of the estimated relationship is low.school quality, moving, segregation, neighbourhoods

Thermoreponsive behaviour of AM(_2)O(_8) materials

This thesis investigates the synthesis and structural characterisation of AM(_2)O(_8) phases, many of which show negative thermal expansion (NTE); relevant literature is reviewed in Chapter One. Chapter Two describes the synthesis, structure solution, and mechanistic role of a new family of low-temperature (LT) orthorhombic AM(_2)O(_8) polymorphs (A(^TV) = Zr, Hf; M(^VI) = Mo, W). These materials are key intermediates in the preparation of cubic AM(_2)O(_8) phases from AM(_2)O(_7)(OH)(_2)(H(_2)O)(_2). The structure of LT-AM(_2)O(_8) has been elucidated by combined laboratory X-ray and neutron powder diffraction. Variable temperature X-ray diffraction (VTXRD) studies have shown LT- AM(_2)O(_8) phases exhibit anisotropic NTE. LT-ZrMo(_2)O(_8) has been shown to undergo spontaneous rehydration, allowing preparation of ZrMo(_2)O(_7)(OD)(_2)(D(_2)O)(_2) and assignment of D(_2)O/OD positions within the structure by neutron diffraction. Using this result, a reversible topotactic dehydration pathway from AM(_2)O(_7)(OH)(_2)(H(_2)O)(_2) to LT-AM(_2)O(_8)s is proposed.Chapter Three investigates the order-disorder phase transition with concurrent oxygen mobility in cubic AM(_2)O(_8) materials; studies include comprehensive VT neutron diffraction of cubic ZrMo(_2)O(_8) to reveal a static to dynamic transition at 215 K, and novel quench-anneal/quench-warm variable temperature/time diffraction experiments on ZrMo(_2)O(_8) which lead to an activation energy of 40 kJmol(^-1) for oxygen migration. In Chapter Four (^17)O-labelled cubic ZrW(_2)O(_8) has been prepared to understand the oxygen migration process by VT MAS NMR. In situ hydrothermal studies of cubicZrMo(_2)O(_8) using synchrotron radiation have shown direct hydration to ZrMo(_2)O(_7)(OH)(_2)(H(_2)O)(_2).. In Chapter Five VTXRD of trigonal a-AMo(_2)O(_8) phases reveals a previously unknown second-order phase transition at 487 K (A = Zr) or 463 K (A = Hf) from P31c to P3ml. Rigid-body Rietveld refinements have shown this is due to alignment of apical Mo-O groups with the c axis in the high-temperature, a' phase

Chromatic thresholds in dense random graphs

The chromatic threshold $\delta_\chi(H,p)$ of a graph $H$ with respect to the random graph $G(n,p)$ is the infimum over $d > 0$ such that the following holds with high probability: the family of $H$-free graphs $G \subset G(n,p)$ with minimum degree $\delta(G) \ge dpn$ has bounded chromatic number. The study of the parameter $\delta_\chi(H) := \delta_\chi(H,1)$ was initiated in 1973 by Erd\H{o}s and Simonovits, and was recently determined for all graphs $H$. In this paper we show that $\delta_\chi(H,p) = \delta_\chi(H)$ for all fixed $p \in (0,1)$, but that typically $\delta_\chi(H,p) \ne \delta_\chi(H)$ if $p = o(1)$. We also make significant progress towards determining $\delta_\chi(H,p)$ for all graphs $H$ in the range $p = n^{-o(1)}$. In sparser random graphs the problem is somewhat more complicated, and is studied in a separate paper.Comment: 36 pages (including appendix), 1 figure; the appendix is copied with minor modifications from arXiv:1108.1746 for a self-contained proof of a technical lemma; accepted to Random Structures and Algorithm

The Millennium Galaxy Catalogue: The nearby supermassive black hole mass function

We highlight the correlation between a galaxy's supermassive black hole mass and the Sersic-index of the host spheroid or bulge component. From our bulge-disk decompositions of 10 095 galaxies, drawn from the Millennium Galaxy Catalogue, we construct the local (z < 0.18) mass function of supermassive black holes. We compare our results to those of McLure & Dunlop (2004) and conclude that the mass density of supermassive black holes may be marginally higher than previously supposed. This increase is predominantly due to the inclusion of low mass and later-type bulges. More details will be presented in a forthcoming paper.Comment: Contributed article to the Fabulous Destiny of Galaxies meetin