Search results for "fixed effects"

COVID-19 y tabaquismo: revisión sistemática y metaanálisis de la evidencia

2021

RESUMEN Objetivo: el objetivo del estudio ha sido responder a las siguientes preguntas: ¿Se asocia el consumo de tabaco en pacientes con Covid-19 con una progresión negativa y desenlace adverso de la enfermedad? y, ¿se asocia el consumo de tabaco, actual y pasado, a una mayor posibilidad de desarrollar COVID-19? Material y Métodos: Se realizó una revisión sistemática (RS) y metaanálisis (MA) de trabajos publicados previamente. La estrategia de búsqueda incluyó todos los descriptores conocidos sobre Covid-19 y tabaco y se realizó en diferentes bases de datos. Se utilizaron modelos estadísticos adecuados para abordar el tamaño del efecto en un metaanálisis: modelo de efectos aleatorios y de e…

On Ignoring the Random Effects Assumption in Multilevel Models: Review, Critique, and Recommendations

2019

Entities such as individuals, teams, or organizations can vary systematically from one another. Researchers typically model such data using multilevel models, assuming that the random effects are uncorrelated with the regressors. Violating this testable assumption, which is often ignored, creates an endogeneity problem thus preventing causal interpretations. Focusing on two-level models, we explain how researchers can avoid this problem by including cluster means of the Level 1 explanatory variables as controls; we explain this point conceptually and with a large-scale simulation. We further show why the common practice of centering the predictor variables is mostly unnecessary. Moreover, …

High Wage Workers Match with High Wage Firms: Clear Evidence of the Effects of Limited Mobility Bias

2012

Positive assortative matching implies that high productivity workers and firms match together. However, there is almost no evidence of a positive correlation between the worker and firm contributions in two-way fixed-effects wage equations. This could be the result of a bias caused by standard estimation error. Using German social security records we show that the effect of this bias is substantial in samples with limited inter-firm movement. The correlation between worker and firm contributions to wage equations is unambiguously positive.

SO2emissions and the environmental Kuznets curve: the case of Chinese provinces

2009

This paper aims at estimating the Environmental Kuznets Curve (EKC) for the sulphur dioxide (SO2) emissions in a panel of 28 Chinese provinces. First, using a fixed effects model, econometric findings reveal an N shape EKC with a turning point of 4500 yuans (index 1990). However, a Chow test reveals a break in 1995, so that the estimation of the model indicates an increasing linear relationship between GDP per capita and SO2 emissions. The previous results imply that the decrease of the Chinese sulphur dioxide emissions during 1996–1999 did not result from the ECK but from an exogenous public action.

The Effects of the Value-Added Tax on Revenue and Inequality

2019

This paper examines the impact of the introduction of the value-added tax on inequality and government revenues using newly released macro data. We present both conventional country fixed effect regressions and instrumental variable analyses, where VAT adoption is instrumented using the previous values of neighbouring countries’ VAT systems as an instrument. The results reveal – in contrast to earlier work – that the revenue consequences of the VAT have not been positive. The results indicate that income-based inequality has increased due to the VAT adoption, whereas consumption inequality has remained unaffected. Peer reviewed

Tirdzniecības atvērtības ietekme uz ekonomikas izaugsmi, CAE valstu empīriskais pētījums

2021

Darba mērķis ir izpētīt tirdzniecības atvērtības ietekmi uz ekonomikas izaugsmi, izmantojot 16 Centrālās un Austrumeiropas valstu paneļa datus 2010. – 2019. gadā, salīdzinot 4 dažādus tirdzniecības atvērtības rādītājus. Apvienotie OLS un fiksētie efekti tiek izmantoti kā primārie novērtētāji, un noturības analīzei tiek izmantots sistēmas GMM tests. Apkopoto OLS un fiksēto šķērsgriezumu regresiju iegūtie rezultāti parāda, ka dažādos tirdzniecības atvērtības mērījumos tirdzniecības atvērtība pozitīvi un ļoti nozīmīgi ietekmē ekonomikas izaugsmi. GMM sistēmas testi parāda tirdzniecības atvērtības negatīvo ietekmi uz ekonomikas izaugsmi, bet nozīmīgumu ieguva tikai divi atvērtības rādītāji.

2019

Abstract This paper examines the labor-market returns to a new form of postsecondary vocational education: vocational master's degrees. We use individual fixed effects models on a matched sample of students and non-students from Finland to capture any time-invariant differences across individuals. We find that attendance in vocational master's programs leads to an earnings increase of more than seven percent five years after entry. The estimated effect remains positive even if selection on unobservables is twice as strong as selection on observables. Earnings gains are similar by gender and age, but they are marginally higher for those in the health sector than for those in the business or …

The impact of corruption on sport demand

2020

PurposeThe article presents an empirical analysis that evaluates the effects of a systemic corruption scandal on the demand in the short and the long run. In 2006, the Calciopoli scandal uncovered the match rigging in the Italian soccer first division. The exemplary sportive sanction of relegating the primary culprit to the second division imposed further negative externalities on the other clubs. Should we prefer the sportive sanction on the team or the monetary fines for the club?Design/methodology/approachWe estimated two log-linear models of the demand side (stadium attendance) using a fixed effect estimator, on two panel data set made of all the Italian soccer clubs in the first and se…

Visualizing the flow of evidence in network meta-analysis and characterizing mixed treatment comparisons

2013

Network meta-analysis techniques allow for pooling evidence from different studies with only partially overlapping designs for getting a broader basis for decision support. The results are network-based effect estimates that take indirect evidence into account for all pairs of treatments. The results critically depend on homogeneity and consistency assumptions, which are sometimes difficult to investigate. To support such evaluation, we propose a display of the flow of evidence and introduce new measures that characterize the structure of a mixed treatment comparison. Specifically, a linear fixed effects model for network meta-analysis is considered, where the network estimates for two trea…

A decade of trials of interferon-alpha for chronic hepatitis C. A meta-regression analysis

2003

The most relevant randomized controlled trials of interferon-alpha (IFN) for naive patients with chronic hepatitis C (CHC) published in a decade, just before appearance of pegylated IFN trials in 2000, were included in this paper. Its purpose is to review the relationship between sustained biochemical response in active versus control group versus usual clinical variables as IFN regimens, cirrhosis, genotype and versus less frequently addressed variables as funding, methodological quality or location of principal author. Meta-analysis estimates of global treatment effect varied according to trial design: group 1=IFN versus placebo/no treatment, 32 RCTs, 2499 pts, OR 9.5 (6.3-14.2); group 2a…