An investigation of new methods for estimating parameter sensitivities

The method proposed for estimating sensitivity derivatives is based on the Recursive Quadratic Programming (RQP) method and in conjunction a differencing formula to produce estimates of the sensitivities. This method is compared to existing methods and is shown to be very competitive in terms of the number of function evaluations required. In terms of accuracy, the method is shown to be equivalent to a modified version of the Kuhn-Tucker method, where the Hessian of the Lagrangian is estimated using the BFS method employed by the RQP algorithm. Initial testing on a test set with known sensitivities demonstrates that the method can accurately calculate the parameter sensitivity

On Minimizing the Risk of Bias in Randomized Controlled Trials in Economics

Estimation of empirical relationships is prone to bias. Economists have carefully studied sources of bias in structural and quasi-experimental approaches, but the randomized control trial (RCT) has only begun to receive such scrutiny. In this paper, we argue that several lessons from medicine, derived from analysis of thousands of RCTs establishing a clear link between certain practices and biased estimates, can be used to reduce the risk of bias in economics RCTs. We identify the subset of these lessons applicable to economics and use them to assess risk of bias in estimates from economics RCTs published between 2001 and 2011. In comparison to medical studies, we find most economics studies do not report important details on study design necessary to assess risk of bias. Many report practices that suggest risk of bias, though this does not necessarily mean bias resulted. We conclude with suggestions on how to remedy these issues

Trends in sensitivity analysis practice in the last decade

Unidad de excelencia María de Maeztu MdM-2015-0552The majority of published sensitivity analyses (SAs) are either local or one factor-at-a-time (OAT) analyses, relying on unjustified assumptions of model linearity and additivity. Global approaches to sensitivity analyses (GSA)which would obviate these shortcomings, are applied by a minority of researchers. By reviewing the academic literature on SA, we here present a bibliometric analysis of the trends of different SA practices in last decade. The review has been conducted both on some top ranking journals (Nature and Science)and through an extended analysis in the Elsevier's Scopus database of scientific publications. After correcting for the global growth in publications, the amount of papers performing a generic SA has notably increased over the last decade. Even if OAT is still the most largely used technique in SA, there is a clear increase in the use of GSA with preference respectively for regression and variance-based techniques. Even after adjusting for the growth of publications in the sole modelling field, to which SA and GSA normally apply, the trend is confirmed. Data about regions of origin and discipline are also briefly discussed. The results above are confirmed when zooming on the sole articles published in chemical modelling, a field historically proficient in the use of SA methods

Three Essays on the Economic Effects of Public Policies

This thesis contributes to the empirical strands of the economic literature that explore and investigate the effects of public policies on individuals and firms. The first chapter provides a novel empirical test of human capital theory by studying whether increases in residual working life induce additional training. By exploiting a sizable pension reform, that affected all Italian workers, in a Difference-in-Differences setting there is evidence that an increase in the residual working life increases human capital investment. Additionally, the response to the reform was very heterogeneous and depending on gender, age profiles, education, martial status, sector of employment and firm size. However, the empirical evidence suggests to rule out that positive variations in human capital investment were directly sponsored by employers. The second chapter studies the impact of the COVID-19 pandemic on female economists' research productivity. The analysis uses data from the SSRN web archive on 4,778 distinct pre-prints involving 8,651 authors from over 90 countries observed from January to November 2020. By estimating a Difference-in-Differences, the estimates show that, since the lockdown began, the number of working papers written by a female economist, alone or jointly with other researchers, uploaded on SSRN declined of about 20 percentage points and this negative effect persists up to about 4 months later. Declines in productivity, however, disappear during the school re-opening period suggesting that indeed childcare demand has been an important channel in causing women production drop. Finally, declines in productivity are not associated with increases in pre-prints' quality. The third chapter provides novel empirical evidence on the effectiveness of public subsidies for SMEs by investigating the effect of a subsidy program taken place in Campania (South Italy) in 2013. By relying on a Difference-in-Differences approach, the empirical analysis demonstrates that the regional program was effective in increasing private firms' spending in innovative investment. However, the firms' response to the program was also largely heterogeneous. In particular, there is evidence that the positive effect on investment comes from micro- and small-sized firms as well as firms operating in high tech sectors and high tech service firms. Nonetheless, it is not possible to reject the hypothesis that firms increased spending by about approximately the amount of the subsidy. Finally, the program had sizeable spillover effects on labour demand but not on firms' productivity

The economic impact of international uncertainties : Sanctioning effects, foreign direct Investment and firm behaviour in Russia

This thesis contributes to following fields of studies: international economics, political economy, international business and industrial organization literature, as well as institutional and innovation economics. In the introductory chapter we provide the necessary foundation for placing the empirical evidence that is presented in Chapters 2 - 4 in a broader economic context. By doing this, the first chapter gives an overview of the main milestones in Russian economic history and outlines Russia's integration into the global economy. Hereby we concentrate on Foreign Direct Investment (FDI) and trade as they are the most relevant components of Russia's globalization process, a process that is currently being reversed as a result of geopolitical tensions. Chapters 2 - 4 form the empirical part of this dissertation. In Chapter 2, we quantify the economic cost for the sanction sender, the EU-27, in the aftermath of the geopolitical crisis, triggered by Russia's involvement in the Ukrainian conflict. We find that direct costs are mainly born by the countries closely connected with Russia in terms of trade, whereas indirect costs are mainly induced by the tight embeddedness in the European trade network. In the empirical part that follows, we turn to the question of whether political risks affect the behaviour of multinational companies (MNCs) in Russia. The research shows that political risks not only affect FDI exits in the host economy, but that their impact is intensified through sanctioning policies. In our final empirical analysis, we take a different perspective that is still highly relevant for an emerging economy stuck in the geopolitical crisis while simultaneously requiring reforms that would guarantee sustainable long-term growth. This growth becomes possible by boosting productivity and building institutions that foster investment in human and physical capital, as well as innovation, in both the high and low-tech manufacturing sectors. Thus, in the empirical study on the innovation-performance link, we scrutinize the factors that might contribute to an improved efficiency of the Russian manufacturing sector

Two Essays on the Management of the West Coast Salmon Fishery

The West Coast salmon fishery presents several complexities that have received little attention in the fisheries economics literature. Two of those complexities are reviewed and analyzed in this dissertation. The first, salmon fishermen participate in alternative fisheries within a season demonstrating a complex switching behavior between different species. Second, the fishery is based on a mixed-stock system where many re-productively isolated sub-populations are harvested simultaneously. In the first essay, I used unique and comprehensive vessel-landing level data describing fishing trips of salmon troll vessels from 2005 to 2014 in a Random Utility Maximization framework. An empirical model is used to determine the effect of closures on the salmon fishery including the distribution of fishermen across fishing locations and alternative fisheries. The results suggest that fishermen respond to area-temporal closures in the salmon fishery by reallocating across space and/or alternative fisheries. This research contributes to the literature by illustrating the importance of fishermen behavior when rent differentials exist across space and species, leading to a complex distribution of effort. In the second essay, I present a spatially explicit mixed-stock system that characterizes the West Coast salmon fishery. I used model simulations to explore the effect that monitoring regimes at different spatial scales of mixed-stock harvest composition have on achieving weak stock escapement goals and economic benefits for the fishery. Results suggest that spatial management of mixed-stock harvest composition allows for higher profits for the fleet -while meeting conservation goals- only when it takes place at fine spatial scales. In general, results of both essays illustrate that ecosystem-based fishery management requires managers to account for the complex behavior of harvesters and the dynamic spatial and ecological interactions of resources