Generalised count distributions for modelling parity

Background: Parametric count distributions customarily used in demography – the Poisson and negative binomial models – do not offer satisfactory descriptions of empirical distributions of completed cohort parity. One reason is that they cannot model variance-to-mean ratios below unity, i.e., underdispersion, which is typical of low-fertility parity distributions. Statisticians have recently revived two generalised count distributions that can model both over- and underdispersion, but they have not attracted demographers’ attention to date. Objective: The objective of this paper is to assess the utility of these alternative general count distributions, namely the Conway-Maxwell-Poisson and gamma count models, for the modeling of distributions of completed parity. Methods: Simulations and maximum-likelihood estimation are used to assess their fit to empirical data from the Human Fertility Database (HFD). Results: The results show that the generalised count distributions offer a dramatically improved fit compared to customary Poisson and negative binomial models in the presence of under- dispersion, without performance loss in the case of equidispersion or overdispersion. Conclusions: This gain in accuracy suggests generalised count distributions should be used as a matter of course in studies of fertility that examine completed parity as an outcome. Contribution: This note performs a transfer of the state of the art in count data modelling and regression in the more technical statistical literature to the field of demography, allowing demographers to benefit from more accurate estimation in fertility research

Time is Money: Disentangling Higher Education Cost-Sharing and Commodification Through Deferred Graduate Retirement

Current higher education policy debates in Europe are increasingly focusing on raising the share of private funding. To date, policy proposals have centred on a relatively small number of alternatives, namely full public funding, tuition fees, either up-front or delayed and income-contingent, or a surtax on graduate incomes. Here, I present an alternative that, to my knowledge, has not been suggested previously, but sidesteps some important objections against other forms of private contributions. The basic idea explored here is to increase the statutory retirement age for higher education graduates relative to non-graduates. In principle, the resulting decrease in future public pension liabilities can be converted into increased funds for present spending on higher education. In this first discussion of the above proposal, I consider important caveats, perform an order-of-magnitude estimate of whether the financial implications of Deferred Graduate Retirement (DGR) are comparable to those of tuition fees, and discuss advantages and disadvantages compared to more established policy options. I conclude that, at least in the continental European context, DGR promises a number of economically and politically desirable properties compared to established alternatives, and deserves more serious investigation

Improving Adult Literacy Without Improving The Literacy of Adults? A Cross-National Cohort Analysis

There is a potential disconnect between adult literacy initiatives on the one hand and the indicators typically employed to operationalize their targets and measure their progress on the other. Specifically, the policy discourse is typically framed in terms of illiterate adults becoming literate, while changes in the main indicator, the overall adult literacy rate, may instead be driven by literate youth becoming adults. The aim of this study is to quantify the relative contribution of these two factors (adult literacy acquisition and cohort replacement) in order to understand the extent to which the latter needs to be taken into account in assessing the progress achieved toward the Education for All (EFA) literacy target. Using DHS data on the education and measured (rather than self-reported) literacy status of women aged 20–49 for 30 countries to examine changes in literacy along cohort lines (while bounding the possible distortion due to migration and differential mortality), I demonstrate how much of the increase in the overall adult literacy rate is due to literate youth becoming adults, rather than illiterate adults becoming literate. The results show that in most countries, observed gains in overall adult literacy greatly overstate the degree to which adults have gained literacy at adult ages. Some countries do exhibit changes in literacy along cohort lines that cannot be easily attributed to selective migration or mortality and may indicate ‘true” gains or losses in individual literacy. The finding that the cohort effect is of large magnitude in practice has significant implications for research on and design of literacy policies: relying on an indicator that conflates two distinct goals, namely of increasing the share of literate adults and of helping illiterate adults become literate, results in misleading policy conclusions. This affects both the retrospective assessment of policy success and failure (and its causes), and the prospective assessment of the challenges in meeting “one size fits all” literacy goals faced by countries with very different population dynamics. This insight is particularly timely given the opportunity presented by the beginning of the new Sustainable Development agenda to reconsider the monitoring of improvements in adult literacy around the globe

What do we mean by school entry age? Conceptual ambiguity and its implications: the example of Indonesia

The age pattern of school entry reflects a complex social and empirical reality that is inadequately captured by a single number. Recognising these complexities in national and international research and policy discourse raises important but neglected questions around the identification of vulnerable groups, the relative value of pre-primary and primary education, as well as the normative powers and responsibilities of governments vis-à-vis parents, and the international educational community vis-à-vis both. This is illustrated by the example of Indonesia, where the official age norm for primary school entry is widely disregarded in practice, with a majority of children starting school one or even two years earlier. Crucially, it is the compliant children entering at the statutory age who tend to be from more disadvantaged households, and enjoy no benefit in educational outcomes from their greater maturity

Credit where credit is due: an approach to education returns based on Shapley values

We propose the use of methods based on the Shapley value to assess the fact that private returns to lower levels of educational attainment should be credited with part of the returns from higher attainment levels, since achieving primary education is a necessary condition to enter secondary and tertiary educational levels. We apply the proposed adjustment to a global dataset of private returns to different educational attainment levels and find that the corrected returns to education imply a large shift of returns from tertiary to primary schooling in countries at all income levels

Modelling SDG scenarios for Educational Attainment and Development. CESDEG: Education for all Global Monitoring Report (EFA-GMR)

The scenarios of educational expansion underlying the population projections presented here result from a further refinement of the education model presented in Lutz et al. (2014). In summary, we project the share of the population ever reaching or exceeding a given attainment level. This is done seperately by country, and gender, but with ‘shrinkage’ within a Bayesian framework (with weakly informative priors). The mean expansion trajectories are modelled as random walks with drift (and potential mean reversion) and independent noise at a probit-transformed scale. The trend parameters are estimated based on reconstructed attainment histories, and extrapolated, subject to additional and some exogenously imposed convergence within regions and between females and males. Under the target scenarios, SDG targets are treated as ‘future data’ (in other words, target trajectories are modeled looking back from 2030 under the assumption that the target will have been met), with a potential trend break in 2015. Limitations shared with all existing global projections of educational development include the fact that in the absence of a detailed theoretical basis, they are forced to rely heavily on statistical extrapolations. For example, there is little consensus on whether “higher education is the new secondary education” (as claimed by Andreas Schleicher of OECD), or is fundamentally different from lower levels of schooling (e.g. in terms of institutional framework, its role in the life cycle, economic returns. In addition, global projections can necessarily not account in a satisfactory manner for idiosyncratic policy changes or shocks. In addition, the specific modelling choices outlined above imply a number of trade-offs. Using highest school attainment as the underlying measure solves many problems associated with historic enrolment data by allowing the consistent reconstruction of time series of attainment from relatively recent cross-sectional data, but comes with challenges of its own. While nevertheless preferable overall, the principal disadvantage of attainment measures deserves mention, namely the relatively long time lag with which outcomes can be observed. Late attainment is common in many developing countries, so that attainment cannot safely be assumed to be ‘final’ until several years above the typical graduation age

Projections of Educational Attainment And Its Development Impacts For Scenarios Of Full and Partial Progress Towards Universal Upper Secondary Schooling. A Report for The International Commission on Financing Global Education Opportunity

It is known that education has strong linkages with virtually all other dimensions of sustainable development, both direct and indirect. Accordingly, trajectories of educational progress towards the Sustainable Development Goals (SDG) education targets are not only of interest on their own terms, but also in terms of their implications for other development outcomes. At the same time, it is clear that for most current low-income countries, meeting the target of universal upper secondary schooling by 2030 outright would require entirely unprecedented rates of expansion that would be extremely challenging to achieve at best. It is highly relevant, therefore, to compare the potential consequences of different scenarios of educational expansion for other development outcomes. Such educational trajectories themselves, like the target, are specified in terms of the participation of school-age children. Many, if not most, of the consequences are determined by the improved education profile of the adult population, however, from whose ranks parents and workers, patients and doctors are drawn. Accordingly, modelling health and economic consequences of educational expansion requires the ability to generate general population projections consistent with given trajectories of educational expansion. The Wittgenstein Centre for Demography and Global Human Capital is a leading centre of expertise in this area and has a proven track record of providing such projections to large-scale international research and policy analysis efforts, including the Intergovernmental Panel on Climate Change (ICCP)

Meeting the Sustainable Development Goals leads to lower world population growth

Here we show the extent to which the expected world population growth could be lowered by successfully implementing the recently agreed-upon Sustainable Development Goals (SDGs). The SDGs include specific quantitative targets on mortality, reproductive health, and education for all girls by 2030, measures that will directly and indirectly affect future demographic trends. Based on a multidimensional model of population dynamics that stratifies national populations by age, sex, and level of education with educational fertility and mortality differentials, we translate these goals into SDG population scenarios, resulting in population sizes between 8.2 and 8.7 billion in 2100. Because these results lie outside the 95% prediction range given by the 2015 United Nations probabilistic population projections, we complement the study with sensitivity analyses of these projections that suggest that those prediction intervals are too narrow because of uncertainty in baseline data, conservative assumptions on correlations, and the possibility of new policies influencing these trends. Although the analysis presented here rests on several assumptions about the implementation of the SDGs and the persistence of educational, fertility, and mortality differentials, it quantitatively illustrates the view that demography is not destiny and that policies can make a decisive difference. In particular, advances in female education and reproductive health can contribute greatly to reducing world population growth

Pressurization of Liquid Oxygen Containers Progress Report No. 7, Nov. 1963 - Nov. 1964

Pressurization of liquid oxygen containers - cryogenic fluid boiling under high and low gravity, liquid hydrogen boiling, injection cooling, and two-dimensional heat transfe

The asymptotic iteration method for the angular spheroidal eigenvalues with arbitrary complex size parameter c

The asymptotic iteration method is applied, to calculate the angular spheroidal eigenvalues $\lambda^{m}_{\ell}(c)$ with arbitrary complex size parameter $c$. It is shown that, the obtained numerical results of $\lambda^{m}_{\ell}(c)$ are all in excellent agreement with the available published data over the full range of parameter values $\ell$, $m$, and $c$. Some representative values of $\lambda^{m}_{\ell}(c)$ for large real $c$ are also given.Comment: 15 pages, 1 figur