IZA DP No. 14839 NOVEMBER 2021 Formalized Employee Search and Labor Demand* Firms often use social networks to find workers, limiting the pool of potential applicants. We conduct a field experiment subsidizing firms’ formal vacancy posting. The subsidies increase non-network employee search and shift vacancies towards high-skilled positions. Post-treatment, firms continue searching for high-skilled workers despite reverting to network-based search. This change in skill requirements does not increase vacancy posting or hiring, suggesting substitutability between workers of different skill levels. Finally, we experimentally show that information asymmetries about applicants’ skills do not limit firms’ formal search. Our results highlight that exposure to different labor market segments can permanently change firms’ labor demand. JEL Classification: D22, J23, J46, C93
Urban expansion is strongly determined by changes in urban population and the density in which new residents settle. Consequently, assessments of future changes in urban area depend on population and density projections. While the former are well-established, the latter have received much less research attention. To fill this void, we set up a time series representing most countries around the globe describing urban population density and several explanatory variables. Using a panel regression approach with country-fixed effects we explain the variation in density levels over time. The results indicate that urban density increases with growing total urban population and decreases with increasing levels of urbanisation. The latter effect diminishes, however, when the urban population fraction increases even further. These results indicate a sequence of increasing, decreasing and stabilising urban densities with increasing urban population shares. This succession can be linked to subsequent development stages of urbanisation, suburbanisation and eventually reurbanisation. The latter stage remains rare in our time series, however, as only a few countries reach the corresponding high urbanisation rates. Furthermore, we find that urban densities decrease with growing national income per capita. This may indicate that higher incomes enable suburbanisation to more dispersed urban areas with larger residences but can also be associated with the advent of smaller households and the growth of non-residential sectors such as industry and commerce. Conversely, urban density increases with higher agricultural land values that we proxy with a novel primary production intensity variable. We use our explanatory results to determine country-specific future urban areas following a commonly applied socio-economic scenario (SSP2) and suggest the total global urban area may triple from 2015 to 2100.
Background Psychotic disorders such as schizophrenia have been associated with older-appearing brain structure, commonly quantified using the brain-age paradigm. However, it remains unclear whether these alterations are present at illness onset and whether antipsychotic treatment modifies their trajectory. Methods In this study, 61 (28 females and 33 males) antipsychotic-naïve people with first-episode psychosis were randomized to receive either a second-generation antipsychotic (risperidone or paliperidone) or placebo over a 6-month treatment period, alongside intensive psychosocial therapy. A healthy control group (n = 27, 17 females, 10 males) was also recruited. Structural MRI scans were collected at baseline, 3 months, and 12 months. Brain age was estimated using two pretrained and validated models (Pyment and CentileBrain). Results Brain-predicted age difference (brain-PAD) did not differ between patients and healthy controls at baseline (F(1,80) = 0.81, p = 0.37). There were also no significant effects of time, treatment group (antipsychotic, placebo, healthy control), or their interaction on brain-PAD across the first year (all p > 0.26). Findings were consistent across both brain-age models, and brain-PAD was not associated with clinical and lifestyle measures. Conclusion These findings suggest that altered structural brain aging is not evident during the earliest stages of psychosis and is not modified by early antipsychotic exposure over the first year of illness. Longer follow-up and approaches that account for illness heterogeneity may be needed to clarify when brain-age alterations emerge in psychotic disorders. Trial registration Australian New Zealand Clinical Trials Registry (http://www.anzctr.org.au/; ACTRN12607000608460).
Tradable Credit Schemes (TCS) have been proposed as a market-based instrument for reducing transport externalities while allowing policymakers to address distributional concerns through the initial allocation of credits. Yet their effectiveness depends on how individuals respond to budgets, prices, and trading opportunities in real-world settings. Evidence from field experiments remains scarce. This paper reports results from a multi-week randomized controlled field trial of a CO2-based TCS for commuting. We implemented the MobilityCoins system with more than 600 participants in a university setting. The intervention assigned individual mobility budgets and priced commuting trips according to their CO2 emissions across multiple travel modes. Our findings show that a TCS can be implemented in a real commuting context and can generate behavioral, distributional, and acceptability benefits. Treated participants reported more changes in commuting behavior than the control group, and econometric estimates indicate emission reductions for specific subgroups. The distance-based allocation produced progressive financial outcomes. The system was also evaluated favorably by a majority of treated participants. At the same time, emission reductions are not uniform across the full sample, and we find no clear evidence that participants responded systematically to variation in MobilityCoins prices. This suggests that the effectiveness of TCS depends on incentive salience, user understanding, and sufficient reduction potential in the target population. Overall, the study provides field evidence that TCS can be a promising and distributionally flexible instrument for sustainable commuting, while identifying key design challenges for future implementations.
Background The etiology and nosological status of seasonal affective disorder (SAD) as a specifier of depressive episodes versus a transdiagnostic disorder are the subject of debate. In this study, we investigated the underlying etiology of SAD and dimensional seasonality by examining their association with latitude and genetic risk for a range of traits, and investigated gene-environment interactions. Methods This study included 12,460 adults (76% female, aged 18–90) with a history of depression from the Australian Genetics of Depression Study. Regression models included predictors for latitude (distance from equator) and polygenic scores for eight traits: major depressive disorder, bipolar disorder, anxiety disorders, chronotype, sleep duration, body mass index, vitamin D levels, and educational attainment. Outcomes were SAD status and general seasonality score. Results SAD was positively associated with latitude (OR[95%CI] = 1.05[1.03–1.06], padjusted < 0.001), and there was nominal evidence of additive and multiplicative interactions between chronotype genetic risk and latitude (β = −0.0014[−0.0024,−0.0003], padjusted = 0.122; OR = 0.98[0.97–1.00], padjusted = 0.122). General seasonality score was associated with latitude (IRR = 1.01[1.01–1.01], padjusted < 0.001) and genetic risk for major depressive disorder (IRR =1.03[1.02–1.04], padjusted < 0.001), bipolar disorder (IRR = 1.02[1.01–1.03], padjusted = 0.001), anxiety disorders (IRR = 1.03[1.01–1.04], padjusted < 0.001), vitamin D levels (OR = 0.89[0.83–0.96], padjusted = 0.048), and educational attainment (IRR = 0.97[0.96–0.98], padjusted < 0.001). Conclusions These findings enhance understanding of SAD etiology, highlighting contributions of psychiatric genetic risk and geographic measures on seasonal behavior, and support examining seasonality as a continuous dimension.
