Comparing Basal Area Diameter Distributions Estimated by Tree Species and for the Entire Stock in a Mixed Stand

Summary

Testing the bivariate distribution of daily equity returns using copulas: an application to the Spanish stock market

In this paper we deal with the identification of dependencies between time series of equity returns. Marginal distribution functions are assumed to be known, and a bivariate chi-square test of fit is applied in a fully parametric copula approach. Several families of copulas are fitted and compared with Spanish stock market data. The results show that the t-copula generally outperforms other dependence structures, and highlight the difficulty in adjusting a significant number of bivariate data series

Incentives and promotion in wage hierarchies

Most of the large firms organization schemes consist in hierarchical structures of tiers with different wage levels. Traditionally the existence of this kind of organizations has been associated to the separation of productive and managerial or supervision tasks and to differences in the skills of the workers. However, many firms now employ workers with similar skills, and then the hierarchical structure can be related to an incentive scheme to ensure that workers supply effort. The model we present investigates how firm owners should determine the optimal wage distribution in order to maximize profits.

Policy -Strategy Option Description, January 30, 2009

Like many states, Iowa faces significant challenges on the energy front.  Energy prices have  surged in recent years to record levels before declining precipitously following the financial  crisis that broke in September 2008.  Despite this pullback, the fundamentals that contributed to  higher energy prices are expected to return once economies rebound. Oil prices have gone up  on increased demand, driven in large part by developing countries such as China and India,  whose economies have been rapidly expanding.  Natural gas prices have also fluctuated  dramatically, trading in a range from $4.50 to $13.00/MMBtu over the past year, but are unlikely  to remain at low levels over the long term.  As shown in our analysis later on in this report, the  difference in levelized cost of electricity from a gas‐fired combined cycle plant can vary  significantly depending on the fuel cost.    Dependence on others for energy supply involves significant risks and uncertainties.  Thus, if  Iowa wishes to reduce its dependence on others – or even achieve energy independence – Iowa  needs to pursue actions on a numbers of fronts.  Following the status quo is not an option.    A carbon tax would change the energy landscape in Iowa.  Since Iowa is currently 75%  dependent on coal, a carbon tax could mean that generators, and in turn ratepayers, could be on  the hook for higher electricity prices, though it remains to be seen exactly what the tax scheme  will be.  In addition to existing plants, a carbon tax would also have a significant impact on the  cost of new generation plant.  We have modeled carbon taxes ranging from $0‐50/ton in our  analysis in the Appendix.  However, if a more aggressive carbon policy came into play resulting  in market values of for example, $100/ton or even $200/ton, then that could raise the cost of coal‐  and gas‐fired generation significantly, making alternatives such as wind more economical.

Effect of interleukin-6 receptor inhibition with tocilizumab in patients with rheumatoid arthritis (OPTION study): a double-blind, placebo-controlled, randomised trial.

BACKGROUND: Interleukin 6 is involved in the pathogenesis of rheumatoid arthritis via its broad effects on immune and inflammatory responses. Our aim was to assess the therapeutic effects of blocking interleukin 6 by inhibition of the interleukin-6 receptor with tocilizumab in patients with rheumatoid arthritis. METHODS: In this double-blind, randomised, placebo-controlled, parallel group phase III study, 623 patients with moderate to severe active rheumatoid arthritis were randomly assigned with an interactive voice response system, stratified by site with a randomisation list provided by the study sponsor, to receive tocilizumab 8 mg/kg (n=205), tocilizumab 4 mg/kg (214), or placebo (204) intravenously every 4 weeks, with methotrexate at stable pre-study doses (10-25 mg/week). Rescue therapy with tocilizumab 8 mg/kg was offered at week 16 to patients with less than 20% improvement in both swollen and tender joint counts. The primary endpoint was the proportion of patients with 20% improvement in signs and symptoms of rheumatoid arthritis according to American College of Rheumatology criteria (ACR20 response) at week 24. Analyses were by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00106548. FINDINGS: The intention-to-treat analysis population consisted of 622 patients: one patient in the 4 mg/kg group did not receive study treatment and was thus excluded. At 24 weeks, ACR20 responses were seen in more patients receiving tocilizumab than in those receiving placebo (120 [59%] patients in the 8 mg/kg group, 102 [48%] in the 4 mg/kg group, 54 [26%] in the placebo group; odds ratio 4.0 [95% CI 2.6-6.1], p<0.0001 for 8 mg/kg vs placebo; and 2.6 [1.7-3.9], p<0.0001 for 4 mg/kg vs placebo). More people receiving tocilizumab than those receiving placebo had at least one adverse event (143 [69%] in the 8 mg/kg group; 151 [71%] in the 4 mg/kg group; 129 [63%] in the placebo group). The most common serious adverse events were serious infections or infestations, reported by six patients in the 8 mg/kg group, three in the 4 mg/kg group, and two in the placebo group. INTERPRETATION: Tocilizumab could be an effective therapeutic approach in patients with moderate to severe active rheumatoid arthritis. FUNDING: F Hoffmann-La Roche, Chugai Pharmaceutical.

New, low estimate for carbon stock in global forest vegetation based on inventory data

Abstract

Local Public-Services Provision under Public-Private Partnerships : Contractual Design and Contracting Parties Incentives

When deciding to resort to a PPP contract for the provision of a local public service, local governments have to consider the demand risk allocation between the contracting parties. In this article, I investigate the effects of demand risk allocation on the accountability of procuring authorities regarding consumers changing demand, as well as on the cost-reducing effort incentives of the private public-service provider. I show that contracts in which the private provider bears demand risk motivate more the public authority from responding to customer needs. This is due to the fact that consumers are empowered when the private provider bears demand risk, that is, they have the possibility to oust the private provider in case of non-satisfaction with the service provision, which provides procuring authorities with more credibility in side-trading and then more incentives to be responsive. As a consequence, I show that there is a lower matching with consumers' preferences over time when demand risk is on the public authority rather than on the private provider, and this is corroborated in the light of two famous case studies. However, contracts in which the private provider does not bear demand risk motivate more the private provider from investing in cost-reducing efforts. I highlight then a tradeoff in the allocation of demand risk between productive and allocative efficiency. The striking policy implication of this article for local governments would be that the current trend towards a greater resort to contracts where private providers bear little or no demand risk may not be optimal. Local governments should impose demand risk on private providers within PPP contracts when they expect that consumers' preferences over the service provision will change over time.

Uncertainty, electoral incentives and political myopia

We study the determinants of political myopia in a rational model of electoral accountability where the key elements are informational frictions and uncertainty. We build aframework where political ability is ex-ante unknown and policy choices are not perfectlyobservable. On the one hand, elections improve accountability and allow to keep well-performing incumbents. On the other, politicians invest too little in costly policies withfuture returns in an attempt to signal high ability and increase their reelection probability.Contrary to the conventional wisdom, uncertainty reduces political myopia and may, undersome conditions, increase social welfare. We use the model to study how political rewardscan be set so as to maximise social welfare and the desirability of imposing a one-term limitto governments. The predictions of our theory are consistent with a number of stylised factsand with a new empirical observation documented in this paper: aggregate uncertainty, measured by economic volatility, is associated to better fiscal discipline in a panel of 20 OECDcountries.

The effects of monetary policy on stock market bubbles: Some evidence

We estimate the response of stock prices to exogenous monetary policy shocks usinga vector-autoregressive model with time-varying parameters. Our evidence points toprotracted episodes in which, after a a short-run decline, stock prices increase persistently in response to an exogenous tightening of monetary policy. That responseis clearly at odds with the "conventional" view on the effects of monetary policy onbubbles, as well as with the predictions of bubbleless models. We also argue that it isunlikely that such evidence be accounted for by an endogenous response of the equitypremium to the monetary policy shocks.

Tailored thoracomyoplasty as a valid treatment option for chronic postlobectomy empyema.

BACKGROUND: Chronic post-lobectomy empyema is rare but may require space obliteration for infection control. We report our experience by using a tailored thoracomyoplasty for this specific indication with respect to infection control and functional outcome. METHODS: We retrospectively analyzed 17 patients (11 men, 6 women) with chronic postlobectomy empyema who were treated by thoracomyoplasty in our institution between 2000 and 2011. All patients underwent an initial treatment attempt by use of chest tube drainage and antibiotics except those with suspicion of pleural aspergillosis (n = 6). In 5 patients, bronchus stump insufficiency was identified at preoperative bronchoscopy. A tailored thoracoplasty was combined with a serratus anterior-rhomboid myoplasty, which also served to close a bronchopleural fistula, if present. The first rib was resected in 11 of 17 patients. RESULTS: The 90-day mortality was 11.7%. Thoracomyoplasty was successful in all surviving patients with respect to infection control, space obliteration, and definitive closure of bronchopleural fistula, irrespective of the type of infection, the presence of a bronchopleural fistula, or whether a first rib resection was performed. Postlobectomy pulmonary function testing before and after thoracoplasty revealed a mean predicted FEV(1) of 63.0% ± 8.5% and 51.5% ± 4.2% (p = 0.01) and a mean predicted DLCO of 59.8% ± 11.6% and 54.5% ± 12.5%, respectively. Postoperative shoulder girdle dysfunction and scoliosis were prevented in patients willing to undergo intense physiotherapy. CONCLUSIONS: Tailored thoracomyoplasty represents a valid option for patients with chronic postlobectomy empyema without requiring a preceding open window thoracostomy. Space obliteration and infection control were equally obtained with and without first rib resection.

Chronic disease management: a qualitative study investigating the barriers, facilitators and incentives perceived by Swiss healthcare stakeholders.

BACKGROUND: Chronic disease management has been implemented for some time in several countries to tackle the increasing burden of chronic diseases. While Switzerland faces the same challenge, such initiatives have only emerged recently in this country. The aim of this study is to assess their feasibility, in terms of barriers, facilitators and incentives to participation. METHODS: To meet our aim, we used qualitative methods involving the collection of opinions of various healthcare stakeholders, by means of 5 focus groups and 33 individual interviews. All the data were recorded and transcribed verbatim. Thematic analysis was then performed and five levels were determined to categorize the data: political, financial, organisational/ structural, professionals and patients. RESULTS: Our results show that, at each level, stakeholders share common opinions towards the feasibility of chronic disease management in Switzerland. They mainly mention barriers linked to the federalist political organization as well as to financing such programs. They also envision difficulties to motivate both patients and healthcare professionals to participate. Nevertheless, their favourable attitudes towards chronic disease management as well as the fact that they are convinced that Switzerland possesses all the resources (financial, structural and human) to develop such programs constitute important facilitators. The implementation of quality and financial incentives could also foster the participation of the actors. CONCLUSIONS: Even if healthcare stakeholders do not have the same role and interest regarding chronic diseases, they express similar opinions on the development of chronic disease management in Switzerland. Their overall positive attitude shows that it could be further implemented if political, financial and organisational barriers are overcome and if incentives are found to face the scepticism and non-motivation of some stakeholders.

Human papillomavirus (HPV) vaccines as an option for preventing cervical malignancies: (how) effective and safe?

We carried out a systematic review of HPV vaccine pre- and post-licensure trials to assess the evidence of their effectiveness and safety. We find that HPV vaccine clinical trials design, and data interpretation of both efficacy and safety outcomes, were largely inadequate. Additionally, we note evidence of selective reporting of results from clinical trials (i.e., exclusion of vaccine efficacy figures related to study subgroups in which efficacy might be lower or even negative from peer-reviewed publications). Given this, the widespread optimism regarding HPV vaccines long-term benefits appears to rest on a number of unproven assumptions (or such which are at odd with factual evidence) and significant misinterpretation of available data. For example, the claim that HPV vaccination will result in approximately 70% reduction of cervical cancers is made despite the fact that the clinical trials data have not demonstrated to date that the vaccines have actually prevented a single case of cervical cancer (let alone cervical cancer death), nor that the current overly optimistic surrogate marker-based extrapolations are justified. Likewise, the notion that HPV vaccines have an impressive safety profile is only supported by highly flawed design of safety trials and is contrary to accumulating evidence from vaccine safety surveillance databases and case reports which continue to link HPV vaccination to serious adverse outcomes (including death and permanent disabilities). We thus conclude that further reduction of cervical cancers might be best achieved by optimizing cervical screening (which carries no such risks) and targeting other factors of the disease rather than by the reliance on vaccines with questionable efficacy and safety profiles.

Goal setting and monetary incentives: when large stakes are not enough

The aim of this paper is to test the effectiveness of wage-irrelevant goal setting policies in a laboratory environment. In our design, managers can assign a goal to their workers by setting a certain level of performance on the work task. We establish our theoretical conjectures by developing a model where assigned goals act as reference points to workers’ intrinsic motivation. Consistent with our model, we find that managers set goals which are challenging but attainable for an average-ability worker. Workers respond to these goals by increasing effort, performance and by decreasing on-the-job leisure activities with respect to the no-goal setting baseline. Finally, we study the interaction between goal setting and monetary rewards and find that goal setting is most effective when monetary incentives are strong. These results suggest that goal setting may produce intrinsic motivation and increase workers’ performance beyond what is achieved using solely monetary incentives.