Robust parent-identifying codes and combinatorial arrays

An $n$-word $y$ over a finite alphabet of cardinality $q$ is called a descendant of a set of $t$ words $x^1,\dots,x^t$ if $y_i\in\{x^1_i,\dots,x^t_i\}$ for all $i=1,\dots,n.$ A code \cC=\{x^1,\dots,x^M\} is said to have the $t$-IPP property if for any $n$-word $y$ that is a descendant of at most $t$ parents belonging to the code it is possible to identify at least one of them. From earlier works it is known that $t$-IPP codes of positive rate exist if and only if $t\le q-1$. We introduce a robust version of IPP codes which allows {unconditional} identification of parents even if some of the coordinates in $y$ can break away from the descent rule, i.e., can take arbitrary values from the alphabet, or become completely unreadable. We show existence of robust $t$-IPP codes for all $t\le q-1$ and some positive proportion of such coordinates. The proofs involve relations between IPP codes and combinatorial arrays with separating properties such as perfect hash functions and hash codes, partially hashing families and separating codes. For $t=2$ we find the exact proportion of mutant coordinates (for several error scenarios) that permits unconditional identification of parents

Empirical Evidence on Occupation and Industry Specific Human Capital

This paper presents instrumental variables estimates of the effects of firm tenure, occupation specific work experience, industry specific work experience, and general work experience on wages using data from the 1979 Cohort of the National Longitudinal Survey of Youth. A key feature of the empirical work presented in this paper is that the returns to human capital are allowed to vary across occupations, in contrast to existing research which has constrained the parameters of the wage equation to be the same across occupations. The estimates indicate that both occupation and industry specific human capital are key determinants of wages, and the importance of various types of human capital varies widely across one-digit occupations. Human capital is primarily occupation specific in occupations such as craftsmen, where workers realize a 14% increase in wages after five years of occupation specific experience but do not realize wage gains from industry specific experience. In contrast, human capital is primarily industry specific in other occupations such as managerial employment where workers realize a 23% wage increase after five years of industry specific work experience. In other occupations, such as professional employment, both occupation and industry specific human capital are key determinants of wages

Competition Among Public Schools: A Reply to Rothstein (2004)

Rothstein has produced two comments, Rothstein (2003) and Rothstein (2004), on Hoxby "Does Competition Among Public Schools Benefit Students and Taxpayers," American Economic Review, 2000. In this paper, I discuss every claim of any importance in the comments. I show that every claim is wrong. I also discuss a number of Rothstein's innuendos--that is, claims that are made by implication rather than with the support of explicit arguments or evidence. I show that, when held up against the evidence, each innuendo proves to be false. One of the major points of Rothstein (2003) is that lagged school districts are a valid instrumental variable for today's school districts. This is not credible. Another major claim of Rothstein (2003) is that it is better to use highly non-representative achievement data based on students' self-selecting into test-taking than to use nationally representative achievement data. This claim is wrong for multiple reasons. The most important claim of Rothstein (2004) is that the results of Hoxby (2000) are not robust to including private school students in the sample. This is incorrect. While Rothstein appears merely to be adding private school students to the data, he actually substitutes error-prone data for error-free data on all students, generating substantial attenuation bias. He attributes the change in estimates to the addition of the private school students, but I show that the change in estimates is actually due to his using erroneous data for public school students. Another important claim in Rothstein (2004) that the results in Hoxby (2000) are not robust to associating streams with the metropolitan areas through which they flow rather than the metropolitan areas where they have their source. This is false: the results are virtually unchanged when the association is shifted from source to flow. Since 93.5 percent of streams flow only in the metropolitan area where they have their source, it would be surprising if the results did change much. The comments Rothstein (2003) and Rothstein (2004) are without merit. All of the data and code used in Hoxby (2000) are available to other researchers. An easy-to-use CD provides not only extracts and estimation code, but all of the raw data and the code for constructing the dataset.

Technical report and user guide: the 2010 EU kids online survey

This technical report describes the design and implementation of the EU Kids Online survey of 9-16 year old internet using children and their parents in 25 countries European countries

Haloes gone MAD: The Halo-Finder Comparison Project

[abridged] We present a detailed comparison of fundamental dark matter halo properties retrieved by a substantial number of different halo finders. These codes span a wide range of techniques including friends-of-friends (FOF), spherical-overdensity (SO) and phase-space based algorithms. We further introduce a robust (and publicly available) suite of test scenarios that allows halo finder developers to compare the performance of their codes against those presented here. This set includes mock haloes containing various levels and distributions of substructure at a range of resolutions as well as a cosmological simulation of the large-scale structure of the universe. All the halo finding codes tested could successfully recover the spatial location of our mock haloes. They further returned lists of particles (potentially) belonging to the object that led to coinciding values for the maximum of the circular velocity profile and the radius where it is reached. All the finders based in configuration space struggled to recover substructure that was located close to the centre of the host halo and the radial dependence of the mass recovered varies from finder to finder. Those finders based in phase space could resolve central substructure although they found difficulties in accurately recovering its properties. Via a resolution study we found that most of the finders could not reliably recover substructure containing fewer than 30-40 particles. However, also here the phase space finders excelled by resolving substructure down to 10-20 particles. By comparing the halo finders using a high resolution cosmological volume we found that they agree remarkably well on fundamental properties of astrophysical significance (e.g. mass, position, velocity, and peak of the rotation curve).Comment: 27 interesting pages, 20 beautiful figures, and 4 informative tables accepted for publication in MNRAS. The high-resolution version of the paper as well as all the test cases and analysis can be found at the web site http://popia.ft.uam.es/HaloesGoingMA

The Effect of Education Policy on Crime: An Intergenerational Perspective

A number of studies have shown that education reforms extending compulsory schooling reduce criminal behavior of those affected by the reform. We consider the effects of a major Swedish educational reform on crime by exploiting its staggered implementation across Sweden. We first show that the reform reduced crime rates for the generation directly affected by the reform. We then show that the benefits extended to the next generation with large reductions in the crime rates of the children of those affected. The effect operates only through the father and points in the direction of improved parenting rather than resources.comprehensive school, economics of crime, returns to education, returns to human capital

Hash-Tree Anti-Tampering Schemes

Procedures that provide detection, location and correction of tampering in documents are known as anti-tampering schemes. In this paper we describe how to construct an anti-tampering scheme using a pre-computed tree of hashes. The main problems of constructing such a scheme are its computational feasibility and its candidate reduction process. We show how to solve both problems by the use of secondary hashing over a tree structure. Finally, we give brief comments on our ongoing work in this area

Addressing Childhood Adversity and Social Determinants inPediatric Primary Care:Recommendations for New Hampshire

Research has clearly demonstrated the significant short- and long-term impacts of adverse childhood experiences (ACEs) and the social determinants of health (SDOH) on child health and well-being.1 Identifying and addressing ACEs and SDOH will require a coordinated and systems-based approach. Pediatric primary care* plays a critical role in this system, and there is a growing emphasis on these issues that may be impacting a family. As awareness of ACEs and SDOH grows, so too does the response effort within the State of New Hampshire. Efforts to address ACEs and the SDOH have been initiated by a variety of stakeholders, including non-profit organizations, community-based providers, and school districts. In late 2017, the Endowment for Health and SPARK NH funded the NH Pediatric Improvement Partnership (NHPIP) to develop a set of recommendations to address identifying and responding to ACEs and SDOH in NH primary care settings caring for children. Methods included conducting a review of literature and Key Informant Interviews (KII). Themes from these were identified and the findings are summarized in this report

On the size of identifying codes in triangle-free graphs

In an undirected graph $G$, a subset $C\subseteq V(G)$ such that $C$ is a dominating set of $G$, and each vertex in $V(G)$ is dominated by a distinct subset of vertices from $C$, is called an identifying code of $G$. The concept of identifying codes was introduced by Karpovsky, Chakrabarty and Levitin in 1998. For a given identifiable graph $G$, let \M(G) be the minimum cardinality of an identifying code in $G$. In this paper, we show that for any connected identifiable triangle-free graph $G$ on $n$ vertices having maximum degree $\Delta\geq 3$, \M(G)\le n-\tfrac{n}{\Delta+o(\Delta)}. This bound is asymptotically tight up to constants due to various classes of graphs including $(\Delta-1)$-ary trees, which are known to have their minimum identifying code of size $n-\tfrac{n}{\Delta-1+o(1)}$. We also provide improved bounds for restricted subfamilies of triangle-free graphs, and conjecture that there exists some constant $c$ such that the bound \M(G)\le n-\tfrac{n}{\Delta}+c holds for any nontrivial connected identifiable graph $G$

ESSENTIAL EMPLOYEES DURING THE COVID-19 CRISIS. ESRI SURVEY AND STATISTICAL REPORT SERIES NUMBER 85 May 2020

• In this report, we use Irish Labour Force Survey data to profile the characteristics of essential workers. We pay particular attention to the family structure, such as whether the employee has children and the age of those children. Given the closure of schools and crèches, this will provide insight into the potential challenges faced by those who are combining work with family responsibilities