Three essays on urban economics : wage inequality, urban sprawl, and labor productivity

The thesis consists of three essays on urban economies. The first essay investigates the relationship between proximity to larger markets and wage distribution within local labor markets. In this essay I derive a theoretical spatial skill demand equation that positively links skill premiums to market access. Using data from U.S. metropolitan areas, I provide evidence that while average wages are higher in metropolitan areas with higher market access, as suggested in the existing literature, the wage differential is unequally distributed across the metropolitan workers. That is, greater access to markets is linked to relatively weaker outcomes for those at the bottom of the wage distribution. The second essay examines the extent of urban sprawl with respect to the volatility of local economies. Specifically, it investigates how uncertainty over future land rents explains changes in the extent of urban sprawl. To theoretically study this relationship, I develop a theoretical model that links sprawl to shocks to changes in land development rent, among other factors. The econometric analysis draws upon panel data from U.S. metropolitan areas over the 1980-2000 censuses. To measure urban sprawl, I construct a distinctive measure that better captures the distribution of population density within metropolitan areas. Using suitable proxy that accounts for uncertainty over future land rents, I provide robust evidence confirming the theoretical prediction. That is, metropolitan areas with higher levels of uncertainty have a lower level of sprawl. Finally, the third essay uses theories from urban production economics to empirically investigate the relationship between the economic performance of U.S. metropolitan areas and their respective amounts of sprawl. Specifically, this essay provides a comprehensive empirical analysis on the impact of urban sprawl on labor productivity. The main finding suggests that higher levels of urban sprawl are negatively associated with average labor productivity. Interestingly, this negative association is even stronger in smaller metropolitan areas. Still, there is evidence that the significance of the negative impact of sprawl is not homogenous across major industries

Geographic Determinants of Hi-Tech Employment Growth in U.S. Counties

This paper examines the spatial pattern of U.S. county employment growth in high-tech industries. The spatial growth dimensions examined include industry cluster effects, urbanization effects, proximity to a college, and proximity in the urban hierarchy. Growth is examined for overall high-tech employment and for employment in various high-tech sectors. Econometric analyses are conducted for a sample of all counties and for metropolitan and non-metropolitan counties separately. Among our primary findings, we do not find evidence of positive localization or cluster growth effects, generally finding negative growth effects. We instead find some evidence of positive urbanization effects and growth penalties for greater distances from larger urban areas.

Geography and high-tech employment growth in U.S. counties

This paper investigates the role of geography in high-tech employment growth across U.S. counties. The geographic dimensions examined include industry cluster effects, urbanization effects, proximity to a research university, and proximity in the urban hierarchy. Growth is assessed for overall high-tech employment and for employment in various high-tech sub-sectors. Econometric analyses are conducted separately for samples of metropolitan and nonmetropolitan counties. Among our primary findings, we do not find evidence of positive localization or within-industry cluster growth effects, generally finding negative growth effects. We instead find evidence of positive urbanization effects and growth penalties for greater distances from larger urban areas. Universities also appear to play their primary role in creating human capital rather than knowledge spillovers for nearby firms. Quantile regression analysis confirms the absence of within-industry cluster effects and importance of human capital for counties with fast growth in high-tech industries

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

The elusive inequality-economic growth relationship: are there differences between cities and the countryside?

R11, O40, O18, E25,

The impact of refugees on employment and wages in Jordan

Starting in 2011, the Syrian conflict caused a large influx of refugees into Jordan. In 2015, there were an estimated 1.3 million Syrians in a country with just 6.6 million Jordanians. This paper investigates the impact of the Syrian refugee influx on the Jordanian labor market. Panel data from 2010 and 2016 combined with information on where the refugee influx was concentrated allow us to identify the impact of refugees on Jordanians’ labor market outcomes. Overall, we find that Jordanians living in areas with a high concentration of refugees have had no worse labor market outcomes than Jordanians with less exposure to the refugee influx