Econometric Models for Count Data with an Application to the Patents-R &amp; D Relationship

Hausman, Jerry A.; Hall, Bronwyn H.; Griliches, Zvi

doi:10.2307/1911191

Cited by 3,002 publications

(1,442 citation statements)

References 14 publications

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“…The second method of estimation is a Negative Binomial fixed effects model (Hausman et al 1984). This count data method fits better the generation of trafficrelated fatalities (Karlaftis and Tarko, 1998;Lord and Mannering, 2010) Finally, laws and regulations are considered in the year in which they were enacted.…”

Section: Methods and Datamentioning

confidence: 99%

The road against fatalities: Infrastructure spending vs. regulation??

Albalate

Fernández

Yarygina

2013

Accident Analysis & Prevention

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Standard-Nutzungsbedingungen:Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden.Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen.Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. Terms of use: Documents in AbstractThe road safety literature is typified by a high degree of compartmentalization between studies that focus on infrastructure and traffic conditions and those devoted to the evaluation of public policies and regulations. As a result, few studies adopt a unified empirical framework in their attempts at evaluating the road safety performance of public interventions, thus limiting our understanding of successful strategies in this regard. This paper considers both types of determinants in an analysis of a European country that has enjoyed considerable success in reducing road fatalities. After constructing a panel data set with road safety outcomes for all Spanish provinces between 1990 and 2009, we evaluate the role of the technical characteristics of infrastructure and recent infrastructure spending together with the main regulatory changes introduced. Our results show the importance of considering both types of determinants in a unified framework. Moreover, we highlight the importance of spending in maintenance given its effectiveness in reducing fatalities and casualties in the current economic context of austerity that is having such a marked impact on investment efforts in Spain.

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Section: Methods and Datamentioning

confidence: 99%

The road against fatalities: Infrastructure spending vs. regulation??

Albalate

Fernández

Yarygina

2013

Accident Analysis & Prevention

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“…Regressions of citation counts reported in this paper are based on the conditional fixed effects Poisson models with robust standard errors. We incorporated journal fixed effects to estimate within-journal effects, and such models can be estimated by a conditional maximum likelihood method which conditions out journal fixed effects [44,45,54]. Specifically, we implemented the xtpoisson function in STATA [55].…”

Section: Robustness Testsmentioning

confidence: 99%

Interdisciplinarity and Impact: Distinct Effects of Variety, Balance and Disparity

2014

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Interdisciplinary research is increasingly recognized as the solution to today's challenging scientific and societal problems, but the relationship between interdisciplinary research and scientific impact is still unclear. This paper studies the association between the degree of interdisciplinarity and the number of citations at the paper level. Different from previous studies compositing various aspects of interdisciplinarity into a single indicator, we use factor analysis to uncover distinct dimensions of interdisciplinarity corresponding to variety, balance, and disparity. We estimate Poisson models with journal fixed effects and robust standard errors to analyze the divergent relationships between these three factors and citations. We find that long-term (13-year) citations (1) increase at an increasing rate with variety, (2) decrease with balance, and (3) increase at a decreasing rate with disparity. Furthermore, interdisciplinarity also affects the process of citation accumulation: (1) although variety and disparity have positive effects on long-term citations, they have negative effects on shortterm (3-year) citations, and (2) although balance has a negative effect on long-term citations, its negative effect is insignificant in the short run. These findings have important implications for interdisciplinary research and science policy.

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“…We therefore estimated mixed-effects count models that acknowledge the data generating process and the nested structure of annual counts of admissions reported for each GP practice. 58,59 We estimated separate models for each admission type and allowed the two QOF indicators MH6 and MH9 (MH4 and MH5 for bipolar admissions) to enter separately (individually) or simultaneously (jointly).…”

Section: Empirical Approachmentioning

confidence: 99%

“…However, the model with gamma distributed effects has a closed form solution and is therefore typically preferred. 59 We did not model the GP practice effects as fixed effects using indicator variables because (1) this would preclude the estimation of PCT fixed effects, and (2) because many of the dependent and independent variables of interest vary little over time, that is, there would be insufficient within-GP practice variation to estimate the model. In order to reduce any potential bias from unobserved practice-specific confounders and make the assumptions underlying EMPIRICAL ANALYSIS NIHR Journals Library www.journalslibrary.nihr.ac.uk the random-effects model more tenable, we included pre-sample baseline admission numbers per GP practice as an additional regressor.…”

Section: Empirical Approachmentioning

confidence: 99%

Do higher primary care practice performance scores predict lower rates of emergency admissions for persons with serious mental illness? An analysis of secondary panel data

Jacobs

Gutacker

Mason

et al. 2015

Health Services and Delivery Research

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BackgroundSerious mental illness (SMI) is a set of chronic enduring conditions including schizophrenia and bipolar disorder. SMIs are associated with poor outcomes, high costs and high levels of disease burden. Primary care plays a central role in the care of people with a SMI in the English NHS. Good-quality primary care has the potential to reduce emergency hospital admissions, but also to increase elective admissions if physical health problems are identified by regular health screening of people with SMIs. Better-quality primary care may reduce length of stay (LOS) by enabling quicker discharge, and it may also reduce NHS expenditure.ObjectivesWe tested whether or not better-quality primary care, as assessed by the SMI quality indicators measured routinely in the Quality and Outcomes Framework (QOF) in English general practice, is associated with lower rates of emergency hospital admissions for people with SMIs, for both mental and physical conditions and with higher rates of elective admissions for physical conditions in people with a SMI. We also tested the impact of SMI QOF indicators on LOS and costs.DataWe linked administrative data from around 8500 general practitioner (GP) practices and from Hospital Episode Statistics for the study period 2006/7 to 2010/11. We identified SMI admissions by a mainInternational Classification of Diseases, 10th revision (ICD-10) diagnosis of F20–F31. We included information on GP practice and patient population characteristics, area deprivation and other potential confounders such as access to care. Analyses were carried out at a GP practice level for admissions, but at a patient level for LOS and cost analyses.MethodsWe ran mixed-effects count data and linear models taking account of the nested structure of the data. All models included year indicators for temporal trends.ResultsContrary to expectation, we found a positive association between QOF achievement and admissions, for emergency admissions for both mental and physical health. An additional 10% in QOF achievement was associated with an increase in the practice emergency SMI admission rate of approximately 1.9%. There was no significant association of QOF achievement with either LOS or cost. All results were robust to sensitivity analyses.ConclusionsPossible explanations for our findings are (1) higher quality of primary care, as measured by QOF may not effectively prevent the need for secondary care; (2) patients may receive their QOF checks post discharge, rather than prior to admission; (3) people with more severe SMIs, at a greater risk of admission, may select into practices that are better organised to provide their care and which have better QOF performance; (4) better-quality primary care may be picking up unmet need for secondary care; and (5) QOF measures may not accurately reflect quality of primary care. Patient-level data on quality of care in general practice is required to determine the reasons for the positive association of QOF quality and admissions. Future research should also aim to identify the non-QOF measures of primary care quality that may reduce unplanned admissions more effectively and could potentially be incentivised.FundingThe National Institute for Health Research Health Services and Delivery Research programme.

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Econometric Models for Count Data with an Application to the Patents-R & D Relationship

Cited by 3,002 publications

References 14 publications

The road against fatalities: Infrastructure spending vs. regulation??

The road against fatalities: Infrastructure spending vs. regulation??

Interdisciplinarity and Impact: Distinct Effects of Variety, Balance and Disparity

Do higher primary care practice performance scores predict lower rates of emergency admissions for persons with serious mental illness? An analysis of secondary panel data

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