Estimating the critical and sensitive periods of investment in early childhood: A methodological note

This paper provides an overview of different quantitative methods available for the statistical analysis of longitudinal data regarding child development, and in particular the identification of critical and sensitive periods for later abilities. It draws heavily on the work on human skill formation developed by the economist James Heckman, which treats ability as a latent variable and explains its formation through the simultaneous estimation of structural equations of investments and achieved abilities across time. We distinguish between two specifications of the ability formation function. One of them (the ‘recursive’) format explains current ability as a function of the ability and investment at the immediately preceding period. The other (the ‘non-recursive’) format explains current ability as a function of a series of past investments. In order to fully examine critical and sensitive periods of investments, the non-recursive formulation needs to be used. Furthermore, true abilities of an individual cannot be directly observed: what we observe are the test scores, for example, on reading and writing. We outline an approach based on structural models that treats actual test scores as measurements of the latent ability variable, and show how it can be used in the recursive and non-recursive formulation. In order to fully examine critical and sensitive periods of investments, we argue that the non-recursive formulation of this structural model is necessary. However, the non-recursive formulation requires more data than the recursive formulation, and to the best of our knowledge, has never been used in the identification of critical and sensitive periods in early childhood development. (254wds

Examining the Link between Crime and Unemployment: A Time Series Analysis for Canada

We use national and regional Canadian data to analyse the relationship between economic activity (as reflected by the unemployment rate) and crime rates. Given potential aggregation bias, we disaggregate the crime data and look at the relationship between six different types of crimes rates and unemployment rate; we also disaggregate the data by region. We employ an error correction model in our analysis to test for short-run and long-run dynamics. We find no evidence of long-run relationship between crime and unemployment, when we look at both disaggregation by type of crime and disaggregation by region. Lack of evidence of a long-run relationship indicates we have no evidence of the motivation hypothesis. For selected types of property crimes, we find some evidence of a significant negative short-run relationship between crime and unemployment, lending support to the opportunity hypothesis. Inclusion of control variables in the panel analysis does not alter the findings, qualitatively or quantitatively

Validity and worth in the science curriculum: learning school science outside the laboratory

It is widely acknowledged that there are problems with school science in many developed countries of the world. Such problems manifest themselves in a progressive decline in pupil enthusiasm for school science across the secondary age range and the fact that fewer students are choosing to study the physical sciences at higher levels and as careers. Responses to these developments have included proposals to reform the curriculum, pedagogy and the nature of pupil discussion in science lessons. We support such changes but argue from a consideration of the aims of science education that secondary school science is too rooted in the science laboratory; substantially greater use needs to be made of out-of-school sites for the teaching of science. Such usage should result in a school science education that is more valid and more motivating and is better at fulfilling defensible aims of school science education. Our contention is that laboratory-based school science teaching needs to be complemented by out-of-school science learning that draws on the actual world (e.g. through fieldtrips), the presented world (e.g. in science centres, botanic gardens, zoos and science museums) and the virtual worlds that are increasingly available through information and communications technologies (ICT)

KIN: a method to infer relatedness from low-coverage ancient DNA

Genetic kinship of ancient individuals can provide insights into their culture and social hierarchy, and is relevant for downstream genetic analyses. However, estimating relatedness from ancient DNA is difficult due to low-coverage, ascertainment bias, or contamination from various sources. Here, we present KIN, a method to estimate the relatedness of a pair of individuals from the identical-by-descent segments they share. KIN accurately classifies up to 3rd-degree relatives using at least 0.05x sequence coverage and differentiates siblings from parent-child pairs. It incorporates additional models to adjust for contamination and detect inbreeding, which improves classification accuracy

BREADR: An R Package for the Bayesian Estimation of Genetic Relatedness from Low-coverage Genotype Data

Robust and reliable estimates of how individuals are biologically related to each other are a key source of information when reconstructing pedigrees. In combination with contextual data, reconstructed pedigrees can be used to infer possible kinship practices in prehistoric populations. However, standard methods to estimate biological relatedness from genome sequence data cannot be applied to low coverage sequence data, such as are common in ancient DNA (aDNA) studies. Critically, a statistically robust method for assessing and quantifying the confidence of a classification of a specific degree of relatedness for a pair of individuals, using low coverage genome data, is lacking.In this paper we present the R-package BREADR (Biological RElatedness from Ancient DNA in R), which leverages the so-called pairwise mismatch rate, calculated on optimally-filtered genome-wide pseudo-haploid sequence data, to estimate genetic relatedness up to the second degree, assuming an underlying binomial distribution. BREADR also returns a posterior probability for each degree of relatedness, from identical twins/same individual, first-degree, second-degree or “unrelated” pairs, allowing researchers to quantify and report the uncertainty, even for very low-coverage data. We show that this method accurately recovers degrees of relatedness forsequence data with coverage as low as 0.04X using simulated data (produced as in Popli etal.(Popli et al., 2023))

Estimating the impact of health on NEET status

This paper uses a dynamic Structural Equation Model of ability formation to investigate the determinants of NEET (not in education, employment or training) status in adolescents, with special focus on health. The model addresses the issue of measurement error in estimating ability and mental health; and explores the determinants of ability and NEET status through time. The analysis finds that ability remains the key predictor of NEET status; and while general health plays an important role in the formation of ability for both girls and boys, the impact of mental health differs between the sexes

Electrochemical decolorization of Reactive Black 5 in an undivided cell using Ti and graphite anodes: Effect of polypyrrole coating on anodes

Electrochemical decolorization of an azo dye Reactive Black 5 (RB5) was studied in an undivided cell using Ti and graphite, and polypyrrole (PPy) coated Ti (PPy-SLS-Ti) and graphite (PPy-SLS-G) anodes in the presence of sodium chloride as an electrolyte to investigate the effect of polypyrrol coating. The colour removal efficiencies were 52.6%, 96.3%, 51.6%, and 41.0% respectively, at the end of 90 minutes of electrolysis at current density of 5 mA/cm2. The presence of PPy coating resulted in lower decolorization than that in the absence of coating. No specific peak emerged in UV-Vis spectra obtained at various time points during electrolysis using uncoated Ti and Graphite anodes which indicated non-selective nature of oxidation process. In case of PPy-SLS/Ti and PPy-SLS/Graphite anodes, a peak at 254 nm emerged distinctly which was determined to be vinylsulfone (VS), an amine. Generation and accumulation of VS suggested that oxidation was suppressed and electrochemical reduction rather than oxidation, was a predominant mechanism responsible for RB5 decolourization in case of polypyrrole coated anodes. Normally, in an undivided cell, reactions on anode predominates (i.e. oxidation). The results obtained here may lead to development of anodes for undivided cells on which the extent of oxidation may be controlled by a suitable coating such as PPy