Cohort Size and Youth Earnings: Evidence from a Quasi-Experiment

In this paper, I use data from the Canadian Labour Force Surveys (LFS), and the 2001 and 2006 Canadian Censuses to estimate the impact of an important labor supply shock on the earnings of young high-school graduates. The abolition of Ontario’s Grade 13 generated a ‘double’ cohort of high-school graduates that simultaneously entered the Ontario labor market, generating a large and sudden increase in the labor supply. This provides a rare occasion to measure the impact of cohort size on earnings without the supply shock being possibly confounded with unobserved trends—a recurring problem in the literature. The Census findings suggest that the effect of the supply shock is statistically and economically important, depressing weekly earnings by 5 to 9 percent. The findings from Census are supported by the LFS results which suggest that the immediate impact of the supply shock—measured about six months after high-school graduation—is also important.Labor Supply Shock, Youth

Estimating the BenefiÂ…t of High School for College-Bound Students

Studies based on instrumental variable techniques suggest that the value of a high school education is large for potential dropouts, yet we know much less about the size of the benefi…t for students who will go on to post-secondary education. To help …fill this gap, I measure the value-added of a year of high-school mathematics for university-bound students using a recent Ontario secondary school reform. The subject speci…ficity of this reform makes it possible to identify the benefi…t of an extra year of mathematics despite the presence of self-selection: one can use subjects unaffected by the reform to control for potential ability differences between control and treatment groups. Further, the richness of the data allows me to generalize the standard difference-in-differences estimator, correcting for heterogeneity in ability measurement across subjects. The estimated value- added to an extra year of mathematics is small for these students –of the order of 17 percent of a standard deviation in university grades. This evidence helps to explain why the literature fi…nds only modest effects of taking more mathematics in high school on wages, the small monetary gain being due to a lack of subject-speci…c human capital accumulation. Within- and between-sample comparisons also suggest that the extra year of mathematics benefi…ts lower-ability students more than higher-ability students.Human Capital, High School Curriculum, Education Reform, Mathematics, Factor Model

Union Membership and Perceived Job Insecurity: 30 Years of Evidence from the American General social Survey

Using the Amercian General Social Survey, we explore the link between union membership and perceived job insecurity. This finding is mainly atributed to the primary and secondary sectors and for recessionary periods. Instrumental-variables estimation and the use of attitudinal proxy variables suggest that the positive correlation union membership and perceived job insecurity is not due to self-selection.Union, Perceived Job Insecurity

Integrability and conformal data of the dimer model

The central charge of the dimer model on the square lattice is still being debated in the literature. In this paper, we provide evidence supporting the consistency of a $c=-2$ description. Using Lieb's transfer matrix and its description in terms of the Temperley-Lieb algebra $TL_n$ at $\beta = 0$, we provide a new solution of the dimer model in terms of the model of critical dense polymers on a tilted lattice and offer an understanding of the lattice integrability of the dimer model. The dimer transfer matrix is analysed in the scaling limit and the result for $L_0-\frac c{24}$ is expressed in terms of fermions. Higher Virasoro modes are likewise constructed as limits of elements of $TL_n$ and are found to yield a $c=-2$ realisation of the Virasoro algebra, familiar from fermionic $bc$ ghost systems. In this realisation, the dimer Fock spaces are shown to decompose, as Virasoro modules, into direct sums of Feigin-Fuchs modules, themselves exhibiting reducible yet indecomposable structures. In the scaling limit, the eigenvalues of the lattice integrals of motion are found to agree exactly with those of the $c=-2$ conformal integrals of motion. Consistent with the expression for $L_0-\frac c{24}$ obtained from the transfer matrix, we also construct higher Virasoro modes with $c=1$ and find that the dimer Fock space is completely reducible under their action. However, the transfer matrix is found not to be a generating function for the $c=1$ integrals of motion. Although this indicates that Lieb's transfer matrix description is incompatible with the $c=1$ interpretation, it does not rule out the existence of an alternative, $c=1$ compatible, transfer matrix description of the dimer model.Comment: 54 pages. v2: minor correction

The ‘Trendiness’ of Sleep: An Empirical Investigation into the Cyclical Nature of Sleep Time

Using Canadian time use data, we exploit exogenous variation in local unemployment rates to investigate the cyclical nature of sleep time and show that for both men and women, sleep time decreases when the economy is doing relatively better. Our results suggest that in a recession Canadians sleep an average of 2 hours and 34 minutes more per week, or 22 minutes more per day. Given the importance of even small changes in sleep time on measures of cognitive functioning such as reaction time and concentration, our findings may help explain the countercyclical nature of mortality. Further, as we find that sleep is affected by the same economic variables (notably the unemployment rate) that affect market work time, our results also contribute to the limited literature that shows that sleep time should not be treated as exogenously determined, but, like any other resource, determined by its relative cost.Business Cycles, Sleep.

On the reality of spectra of Uq(sl2)\boldsymbol{U_q(sl_2)}-invariant XXZ Hamiltonians

A new inner product is constructed on each standard module over the Temperley-Lieb algebra $\mathsf{TL}_n(\beta)$ for $\beta\in \mathbb R$ and $n \ge 2$. On these modules, the Hamiltonian $h = -\sum_i e_i$ is shown to be self-adjoint with respect to this inner product. This implies that its action on these modules is diagonalisable with real eigenvalues. A representation theoretic argument shows that the reality of spectra of the Hamiltonian extends to all other Temperley-Lieb representations. In particular, this result applies to the celebrated $U_q(sl_2)$-invariant XXZ Hamiltonian, for all $q+q^{-1}\in \mathbb R$.Comment: 30 page

Combination of LC-MS and CE-MS Analysis for the Separation and the Identification of Phosphonic Acids

The analysis of phosphonic acids in a spiked tap water has been investigated by capillary electrophoresis-mass spectrometry (CE-MS) and liquid chromatography-mass spectrometry (LC-MS) as part of the Third Official Proficiency Test of the Organization for the Prohibition of Chemical Weapons. The use of a non-volatile electrolyte (5 mM sorbic acid/ammonia, pH 6.5) in CE and a volatile mobile phase (water/0.1 v/v trifluoroacetic acid/acetonitrile) in LC achieves the baseline resolution of studied phosphonic acids. Tandem-MS detection analysis allows an accurate identification of these solutes by screening their characteristic fragmentations