A delimitation of the support of optimal designs for Kiefer's ϕp\phi_p-class of criteria

The paper extends the result of Harman and Pronzato [Stat. & Prob. Lett., 77:90--94, 2007], which corresponds to $p=0$, to all strictly concave criteria in Kiefer's $\phi_p$-class. Let $\xi$ be any design on a compact set $X\subset\mathbb{R}^m$ with a nonsingular information matrix \Mb(\xi), and let $\delta$ be the maximum of the directional derivative $F_{\phi_p}(\xi,x)$ over all $x\in X$. We show that any support point $x_*$ of a $\phi_p$-optimal design satisfies the inequality F_{\phi_p}(\xi,x_*) \geq h_p[\Mb(\xi),\delta], where the bound h_p[\Mb(\xi),\delta] is easily computed: it requires the determination of the unique root of a simple univariate equation (polynomial when $p$ is integer) in a given interval. The construction can be used to accelerate algorithms for $\phi_p$-optimal design and is illustrated on an example with $A$-optimal design

Are Lone Mothers Responsive to Policy Changes? Evidence from a Workfare Reform in a Generous Welfare State

There is a heated debate in many European countries about a move towards a welfare system that increases the incentives for lone mothers to move off welfare and into work. We analyze the consequences of a major Norwegian workfare reform of the generous welfare system for lone mothers. Our difference-in-differences estimates show that the policy changes were successful in improving labor market attachment and increasing disposable income of new lone mothers. By contrast, the reform led to a substantial decrease in disposable income and a significant increase in poverty among persistent lone mothers, because a sizeable group was unable to offset the loss of out-of-work welfare benefits with gains in earnings. This suggests that the desired effects of the workfare reform were associated with the side-effects of income loss and increased poverty among a substantial number of lone mothers with insurmountable employment barriers. This finding stands in stark contrast to evidence from similar policy changes in Canada, the UK, and the US, and underscores that policymakers from other developed countries should be cautious when drawing lessons from the successful welfare reforms implemented in Anglo-Saxon countries.lone mothers, workfare reform, difference-in-differences, heterogeneity, earnings, labor force participation, poverty, disposable income

An extended Generalised Variance, with Applications

We consider a measure $\psi$ k of dispersion which extends the notion of Wilk's generalised variance, or entropy, for a d-dimensional distribution, and is based on the mean squared volume of simplices of dimension k $\le$ d formed by k + 1 independent copies. We show how $\psi$ k can be expressed in terms of the eigenvalues of the covariance matrix of the distribution, also when a n-point sample is used for its estimation, and prove its concavity when raised at a suitable power. Some properties of entropy-maximising distributions are derived, including a necessary and sufficient condition for optimality. Finally, we show how this measure of dispersion can be used for the design of optimal experiments, with equivalence to A and D-optimal design for k = 1 and k = d respectively. Simple illustrative examples are presented.Comment: Corrected references and typos Added figure

Great Expectations: The Determinants of Female University Enrolment in Europe

We empirically investigate the determinants of the female decision of investing in post-secondary education, focusing on the role played by the context where young women take their education decision. We first develop a stylized two-period model to analyze the female decision of investing in education and highlight two main determinants: the time to be devoted to child care and the probability of working in a skilled job. We then use data on educational decisions of women in the 17-21 age group drawn from EU-Silc, available for the years 2004-2008. From the same survey we construct context indicators at the regional level, and exploit regional variability to identify how women’s educational investment reacts to changes in the surrounding context. We find that the share of working women with children below 5 and the share of women with managerial positions or self-employed positively affect the probability that women enrol in post-secondary education. The same does not hold for men.post-secondary education, university, child care time requirement, managerial positions, self-employment, context, EU-Silc data, repeated cross-section

Efficient Prediction Designs for Random Fields

For estimation and predictions of random fields it is increasingly acknowledged that the kriging variance may be a poor representative of true uncertainty. Experimental designs based on more elaborate criteria that are appropriate for empirical kriging are then often non-space-filling and very costly to determine. In this paper, we investigate the possibility of using a compound criterion inspired by an equivalence theorem type relation to build designs quasi-optimal for the empirical kriging variance, when space-filling designs become unsuitable. Two algorithms are proposed, one relying on stochastic optimization to explicitly identify the Pareto front, while the second uses the surrogate criteria as local heuristic to chose the points at which the (costly) true Empirical Kriging variance is effectively computed. We illustrate the performance of the algorithms presented on both a simple simulated example and a real oceanographic dataset

Exploring the impacts of public childcare on mothers and children in Italy: does rationing play a role?

This paper investigates the effects of public childcare availability in Italy on mothers' working status and children's scholastic achievements. We use a newly available dataset containing individual standardized test scores of pupils attending second grade of primary school in 2008-09 in conjunction with data on public childcare availability. Public childcare coverage in Italy is scarce (12.7 percent versus the OECD average of 30 percent) and the service is "rationed": each municipality allocates the available slots according to eligibility criteria. We contribute to the existing literature taking into account rationing in public childcare access and the functioning of childcare market. Our estimates indicate that childcare availability has positive and significant effects on both mothers' working status and children's language test scores. The effects are stronger when the degree of rationing is high and for low educated mothers and children living in lower income areas of the country.childcare; female employment; child cognitive outcomes

Exploring the Impacts of Public Childcare on Mothers and Children in Italy: Does Rationing Play a Role?

This paper investigates the effects of public childcare availability in Italy on mothers' working status and children's scholastic achievements. We use a newly available dataset containing individual standardized test scores of pupils attending second grade of primary school in 2008-09 in conjunction with data on public childcare availability. Public childcare coverage in Italy is scarce (12.7 percent versus the OECD average of 30 percent) and the service is “rationed”: each municipality allocates the available slots according to eligibility criteria. We contribute to the existing literature taking into account rationing in public childcare access and the functioning of the childcare market. Our estimates indicate that childcare availability has positive and significant effects on both mothers' working status and children's language test scores. The effects are stronger when the degree of rationing is high and for low educated mothers and children living in lower income areas of the country.childcare, female employment, child cognitive outcomes