The computation of the cohomology rings of all groups of order 128

We describe the computation of the mod-2 cohomology rings of all 2328 groups of order 128. One consequence is that all groups of order less than 256 satisfy the strong form of Benson's Regularity Conjecture.Comment: 15 pages; revised versio

Minimum wage setting and standards of fairness

We examine the setting of minimum wages, arguing that they can best be understood as a reflection of voters' notions of fairness. We arrive at this conclusion through an empirical investigation of the implications of three models, considered in the context of policy setting by sub-units in a federation: a competing interests group model; a constrained altruism model; and a fairness based model. In the latter model, voters are interested in banning what they view to be unfair transactions, with the notion of fairness based on comparisons to the "going" unskilled wage. We use data on minimum wages set in the ten Canadian provinces from 1969 to 2005 to carry out the investigation. A key implication of the models that is borne out in the data is that minimum wages should be set as a positive function of the location of the unskilled wage distribution. Together, the results indicate that minimum wages are set according to a "fairness" standard and that this may exacerbate movements in inequality.

Understanding the wage patterns of Canadian less skilled workers: the role of implicit contracts

We examine the wage patterns of Canadian less skilled male workers over the last quarter century by organizing workers into job entry cohorts. We find entry wages for successive cohorts declined until 1997, and then began to recover. Wage profiles steepened for cohorts entering after 1997, but not for cohorts entering in the 1980s - a period when start wages were relatively high. We argue that these patterns are consistent with a model of implicit contracts with recontracting in which a worker's current wage is determined by the best labour market conditions experienced during the current job spell.

Short-range ultrasonic communications in air using quadrature modulation

A study has been undertaken of ultrasonic communications methods in air, using a quadrature modulation method. Simulations were first performed to establish the likely performance of quadrature phase shift keying over the limited bandwidth available in an ultrasonic system. Quadrature phase shift keying modulation was then implemented within an experimental communication system, using capacitive ultrasonic sources and receivers. The results show that such a system is feasible in principle for communications over distances of several meters, using frequencies in the 200 to 400 kHz range

Literacy, Numeracy and Labour Market Outcomes in Canada

Most research on the contribution of human capital to economic growth and its role in the distribution of income uses indirect measures of human capital such as educational attainment and work experience. Such measures are arguably inputs into the production of human capital in the form of skills, competencies and knowledge. This study uses Canadian data from the international Adult Literacy Survey to analyse the role of directly observed skills -- specifically, prose, document and quantitative literacy -- on individual labour market earnings. The contributions of unobserved skills are taken into account using input measures (education and experience). We find that literacy skills have a large and statistically significant causal effect on earnings. As much as one-third of the return to education may be due to the combined effects of education on literacy and of literacy skills on earnings. In contrast, very little of the return to labour market experience is associated with the combined effects of experience on literacy and literacy skills on earnings.

Ability, Parental Valuation of Education and the High School Dropout Decision

We use a large, rich Canadian micro-level dataset to examine the channels through which family socio-economic status and unobservable characteristics affect children's decisions to drop out of high school. First, we document the strength of observable socio-economic factors: our data suggest that teenage boys with two parents who are themselves high school dropouts have a 16% chance of dropping out, compared to a dropout rate of less than 1% for boys whose parents both have a university degree. We examine the channels through which this socio-economic gradient arises using an extended version of the factor model set out in Carneiro, Hansen, and Heckman (2003). Specifically, we consider the impact of cognitive and non-cognitive ability and the value that parents place on education. Our results support three main conclusions. First, cognitive ability at age 15 has a substantial impact on dropping out. Second, parental valuation of education has an impact of approximately the same size as cognitive ability effects for medium and low ability teenagers. A low ability teenager has a probability of dropping out of approximately .03 if his parents place a high value on education but .36 if their education valuation is low. Third, parental education has no direct effect on dropping out once we control for ability and parental valuation of education. Our results point to the importance of whatever determines ability at age 15 (including, potentially, early childhood interventions) and of parental valuation of education during the teenage years. We also make a small methodological contribution by extending the standard factor based estimator to allow a non-linear relationship between the factors and a covariate of interest. We show that allowing for non-linearities has a substantial impact on estimated effects.Idiosyncratic Shocks, Disability, Insurance, Marriage

Ability, parental valuation of education and the high school dropout decision

We use a large, rich Canadian micro-level dataset to examine the channels through which family socio-economic status and unobservable characteristics affect children's decisions to drop out of high school. First, we document the strength of observable socio-economic factors: our data suggest that teenage boys with two parents who are themselves high school dropouts have a 16 per cent chance of dropping out, compared to a dropout rate of less than 1 per cent for boys whose parents both have a university degree. We examine the channels through which this socio-economic gradient arises using an extended version of the factor model set out in Carneiro, Hansen, and Heckman (2003). Specifically, we consider the impact of cognitive and non-cognitive ability and the value that parents place on education. Our results support three main conclusions. First, cognitive ability at age 15 has a substantial impact on dropping out. The highest ability individuals are predicted never to drop out regardless of parental education or parental valuation of education. In contrast, the lowest ability teenagers have a probability of dropping out of approximately .36 if their parents have a low valuation of education. Second, parental valuation of education has a substantial impact on medium and low ability teenagers. A low ability teenager has a probability of dropping out of approximately .03 if his parents place a high value on education but .36 if their educational valuation is low. These effects are estimated while conditioning on ability at age 15. Thus, under some assumptions, they reflect parental influences during the upper teenage years and are in addition to any impact they might have in the early childhood years leading up to age 15. Third, parental education has no direct effect on dropping out once we control for ability and parental valuation of education. Overall, our results point to the importance of whatever determines ability at age 15 (including, potentially, early childhood interventions) and of parental valuation of education during the teenage years. Our work also provides a small methodological contribution by extending the standard factor based estimator to allow a more non-linear relationship between the factors and a co-variate of interest. We show that allowing for non-linearities has a substantial impact on estimated effects.

Spill-Overs from Good Jobs

Does attracting or losing jobs in high paying sectors have important spill-over effects on wages in other sectors? The answer to this question is central to a proper assessment of many trade and industrial policies. In this paper, we explore this question by examining how predictable changes in industrial composition in favor of high paying sectors affect wage determination at the industry-city level. In particular, we use US Census data over the years 1970 to 2000 to quantify the relationship between changes in industry-specific city-level wages and changes in industrial composition. Our finding is that the spill-over (i.e., general equilibrium) effects associated with changes in the fraction of jobs in high paying sectors are very substantial and persistent. Our point estimates indicate that the total effect on average wages of a change in industrial composition that favors high paying sectors is about 3.5 times greater than that obtained from a commonly used composition-adjustment approach which neglects general equilibrium effects. We interpret our results as being most likely driven by a variant of the mechanism recently emphasized in the heterogenous firm literature whereby changes in competitive pressure cause a reallocation of employment toward the most efficient firms.