Research

Work in Progress

We establish identifying assumptions and estimation procedures for the ATT in a Difference-in-Differences setting with staggered treatment adoption in the presence of spillovers. We show that the ATT can be estimated by a simple TWFE method that extends the approach of Wooldridge [2022]’s fully interacted regression model. We broaden our framework to the non-linear case of count data, offering estimation of the ATT by a simple TWFE Poisson model, and we revisit a corresponding application from the crime literature. Monte Carlo simulations show that our estimator performs competitively. 

We investigate the direct and spillover effects of geographically targeted crime prevention policies. These policies mandated the cessation of alcohol service in pubs, bars, and nightclubs in two of the main entertainment precincts in Sydney, Australia. 

Publications

Oxford Bulletin of Economics and Statistics, Volume 83, Issue6, 2021

Whenever treatment effects are heterogeneous, and there is sorting into treatment based on the gain, monotonicity is a condition that both instrumental variable (IV) and fuzzy regression discontinuity (RD) designs must satisfy for their estimate to be interpretable as a local average treatment effect. However, applied economic work often omits a discussion of this important assumption. A possible explanation for this missing step is the lack of a clear framework to think about monotonicity in practice. In this paper, we use an extended Roy model to provide insights into the interpretation of IV and fuzzy RD estimates under various degrees of treatment effect heterogeneity, sorting on gain and violation of monotonicity. We then extend our analysis to two applied settings to illustrate how monotonicity can be investigated using a mix of economic insights, data patterns and formal tests. For both settings, we use a Roy model to interpret the estimate even in the absence of monotonicity. We conclude with a set of recommendations for the applied researcher.

- Journal of Labor Economics, vol. 32, Issue 4, 2014

The allocation of children’s time among different activities may be important for cognitive and noncognitive development. Here, we exploit time use diaries from the Longitudinal Study of Australian Children to study the effects of time allocation. By doing so, we characterize the trade-off between different activities to which a child is exposed. On the one hand, our results suggest that time spent in educational activities, particularly with parents, is the most productive input for cognitive skill development. On the other hand, noncognitive skills appear insensitive to alternative time allocations. Instead, they are greatly affected by the mother’s parenting style.

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- Journal of Applied Econometrics, Volume 27, Issue 5, 2012

The purpose of this paper is to build a dynamic structural model of educational choices in which cognitive skills shape decisions. The model is estimated by maximum likelihood using cohort data where individuals are observed from birth to the middle of their working life. These data are unique in that they include cognitive skills test scores collected as early as age 7. We then investigate how alternative policies foster educational enrolment. In particular, we simulate the effect of two subsidies different in the timing of disbursement. The first consists of grants assigned directly to individuals aged between 16 and 18. The second is assigned to the parents earlier on, when the cohort is still in its childhood. The latter subsidy affects cognitive skills accumulation and in turn educational choices. Our results suggest that a grant fosters enrolment at the lowest cost but the parental income subsidy generates more welfare as measured by a class of social welfare functions. Nevertheless, these differences in costs and welfare are small. Overall, the results reinforce the view that government investments in cognitive skill accumulation during childhood are worthwhile. However, the results also indicate that such investments should be well structured to ensure a high return.

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- Journal of Applied Econometrics, Volume 27, Issue 1, 2012

The aim of this paper is to test for stochastic monotonicity in intergenerational socio-economic mobility tables. In other words, we question whether having a parent from a high socio-economic status is never worse than having one with a lower status. Using existing inferential procedures for testing unconditional stochastic monotonicity, we first test a set of 149 intergenerational mobility tables in 35 different countries and find that monotonicity cannot be rejected in hardly any table. In addition, we propose new testing procedures for testing conditional stochastic monotonicity and investigate whether monotonicity still holds after conditioning on a number of covariates such as education, cognitive and non-cognitive skills. Based on the NCDS cohort data from the UK, our results provide evidence that monotonicity holds, even conditionally. Moreover, we do not find large differences in our results when comparing social class and wage class mobility.

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- Economics of Education Review, Volume 29, Issue 1, 2010

In this paper we investigate the effect of using a home computer on children’s development. In most OECD countries 70% or more of the households have a computer at home and children use computers quite extensively, even at very young ages. We use data from the Longitudinal Study of Australian Children (LSAC), which follows an Australian cohort born in 1999/2000. Skills and computer usage information is collected when children are approximately 5 and 7 years old. For cognitive skills, our results indicate that computer time has a positive effect. For non-cognitive skills the evidence is mixed, the effect depending on the score and the age of the children. We test the robustness of our results by comparing OLS, IV and Value Added estimators. Generally, the IV estimates are larger and the Value Added estimates lower than the OLS ones. However the pattern of the results is quite consistent.