996 resultados para Property testing
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I show that intellectual property rights yield static efficiency gains, irrespective oftheir dynamic role in fostering innovation. I develop a property-rights model of firmorganization with two dimensions of non-contractible investment. In equilibrium, thefirst best is attained if and only if ownership of tangible and intangible assets is equallyprotected. If IP rights are weaker, firm structure is distorted and efficiency declines:the entrepreneur must either integrate her suppliers, which prompts a decline in theirinvestment; or else risk their defection, which entails a waste of her human capital. Mymodel predicts greater prevalence of vertical integration where IP rights are weaker,and a switch from integration to outsourcing over the product cycle. Both empiricalpredictions are consistent with evidence on multinational companies. As a normativeimplication, I find that IP rights should be strong but narrowly defined, to protect abusiness without holding up its potential spin-offs.
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Adopting a simplistic view of Coase (1960), most economic analyses of property rightsdisregard both the key advantage that legal property rights (that is, in rem rights) provide torightholders in terms of enhanced enforcement, and the difficulties they pose to acquirers interms of information asymmetry about legal title. Consequently, these analyses tend to overstatethe role of "private ordering" and disregard the two key elements of property law: first, theessential conflict between property (that is, in rem) enforcement and transaction costs; and,second, the institutional solutions created to overcome it, mainly contractual registries capable ofmaking truly impersonal (that is, asset-based) trade viable when previous relevant transactionson the same assets are not verifiable by judges. This paper fills this gap by reinterpreting bothelements within the Coasean framework and thus redrawing the institutional foundations of bothproperty and corporate contracting.
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In a weighted spatial network, as specified by an exchange matrix, the variances of the spatial values are inversely proportional to the size of the regions. Spatial values are no more exchangeable under independence, thus weakening the rationale for ordinary permutation and bootstrap tests of spatial autocorrelation. We propose an alternative permutation test for spatial autocorrelation, based upon exchangeable spatial modes, constructed as linear orthogonal combinations of spatial values. The coefficients obtain as eigenvectors of the standardised exchange matrix appearing in spectral clustering, and generalise to the weighted case the concept of spatial filtering for connectivity matrices. Also, two proposals aimed at transforming an acessibility matrix into a exchange matrix with with a priori fixed margins are presented. Two examples (inter-regional migratory flows and binary adjacency networks) illustrate the formalism, rooted in the theory of spectral decomposition for reversible Markov chains.
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This study aims to identify the constraints that complicate the assessment of speaking in Capeverdean EFL classrooms. A literature review was conducted on studies already done in the field of testing speaking in EFL Capeverdean classrooms. The study was carried out using qualitative method with some Capeverdean secondary school English teachers. The participants answered a questionnaire that asked teachers opinions and experiences about speaking assessment. The study found that Capeverdean English teachers do not adequately assess their students speaking ability. Therefore, the study pointed out the constraints of the Capeverdean context that complicate the assessment of speaking in EFL classrooms. The teachers reported the main constraints in order of significance as large classes, difficulty in marking oral tests, difficulty in designing oral tests and difficulty in separating the speaking skill from the listening skill. It concluded that Capeverdean English teachers need assistance with new tools to assess speaking in their classrooms. Thus, the author will make some suggestions, first to the Ministry of Education and then to English teachers in the field to assist them with the implementation of regular oral testing in Cape Verdean English classrooms.
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BACKGROUND: Replicative phenotypic HIV resistance testing (rPRT) uses recombinant infectious virus to measure viral replication in the presence of antiretroviral drugs. Due to its high sensitivity of detection of viral minorities and its dissecting power for complex viral resistance patterns and mixed virus populations rPRT might help to improve HIV resistance diagnostics, particularly for patients with multiple drug failures. The aim was to investigate whether the addition of rPRT to genotypic resistance testing (GRT) compared to GRT alone is beneficial for obtaining a virological response in heavily pre-treated HIV-infected patients. METHODS: Patients with resistance tests between 2002 and 2006 were followed within the Swiss HIV Cohort Study (SHCS). We assessed patients' virological success after their antiretroviral therapy was switched following resistance testing. Multilevel logistic regression models with SHCS centre as a random effect were used to investigate the association between the type of resistance test and virological response (HIV-1 RNA <50 copies/mL or ≥1.5 log reduction). RESULTS: Of 1158 individuals with resistance tests 221 with GRT+rPRT and 937 with GRT were eligible for analysis. Overall virological response rates were 85.1% for GRT+rPRT and 81.4% for GRT. In the subgroup of patients with >2 previous failures, the odds ratio (OR) for virological response of GRT+rPRT compared to GRT was 1.45 (95% CI 1.00-2.09). Multivariate analyses indicate a significant improvement with GRT+rPRT compared to GRT alone (OR 1.68, 95% CI 1.31-2.15). CONCLUSIONS: In heavily pre-treated patients rPRT-based resistance information adds benefit, contributing to a higher rate of treatment success.
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This paper discusses the role of deterministic components in the DGP and in the auxiliaryregression model which underlies the implementation of the Fractional Dickey-Fuller (FDF) test for I(1) against I(d) processes with d [0, 1). This is an important test in many economic applications because I(d) processess with d < 1 are mean-reverting although, when 0.5 = d < 1, like I(1) processes, they are nonstationary. We show how simple is the implementation of the FDF in these situations, and argue that it has better properties than LM tests. A simple testing strategy entailing only asymptotically normally distributedtests is also proposed. Finally, an empirical application is provided where the FDF test allowing for deterministic components is used to test for long-memory in the per capita GDP of several OECD countries, an issue that has important consequences to discriminate between growth theories, and on which there is some controversy.
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Small sample properties are of fundamental interest when only limited data is avail-able. Exact inference is limited by constraints imposed by speci.c nonrandomizedtests and of course also by lack of more data. These e¤ects can be separated as we propose to evaluate a test by comparing its type II error to the minimal type II error among all tests for the given sample. Game theory is used to establish this minimal type II error, the associated randomized test is characterized as part of a Nash equilibrium of a .ctitious game against nature.We use this method to investigate sequential tests for the di¤erence between twomeans when outcomes are constrained to belong to a given bounded set. Tests ofinequality and of noninferiority are included. We .nd that inference in terms oftype II error based on a balanced sample cannot be improved by sequential sampling or even by observing counter factual evidence providing there is a reasonable gap between the hypotheses.
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The paper proposes a technique to jointly test for groupings of unknown size in the cross sectional dimension of a panel and estimates the parameters of each group, and applies it to identifying convergence clubs in income per-capita. The approach uses the predictive density of the data, conditional on the parameters of the model. The steady state distribution of European regional data clusters around four poles of attraction with different economic features. The distribution of incomeper-capita of OECD countries has two poles of attraction and each grouphas clearly identifiable economic characteristics.
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Due to practical difficulties in obtaining direct genetic estimates of effective sizes, conservation biologists have to rely on so-called 'demographic models' which combine life-history and mating-system parameters with F-statistics in order to produce indirect estimates of effective sizes. However, for the same practical reasons that prevent direct genetic estimates, the accuracy of demographic models is difficult to evaluate. Here we use individual-based, genetically explicit computer simulations in order to investigate the accuracy of two such demographic models aimed at investigating the hierarchical structure of populations. We show that, by and large, these models provide good estimates under a wide range of mating systems and dispersal patterns. However, one of the models should be avoided whenever the focal species' breeding system approaches monogamy with no sex bias in dispersal or when a substructure within social groups is suspected because effective sizes may then be strongly overestimated. The timing during the life cycle at which F-statistics are evaluated is also of crucial importance and attention should be paid to it when designing field sampling since different demographic models assume different timings. Our study shows that individual-based, genetically explicit models provide a promising way of evaluating the accuracy of demographic models of effective size and delineate their field of applicability.
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This Article breaks new ground toward contractual and institutional innovation in models of homeownership, equity building, and mortgage enforcement. Inspired by recent developments in the affordable housing sector and other types of public financing schemes, we suggest extending institutional and financial strategies such as time- and place-based division of property rights, conditional subsidies, and credit mediation to alleviate the systemic risks of mortgage foreclosure. Two new solutions offer a broad theoretical basis for such developments in the economic and legal institution of homeownership: a for-profit shared equity scheme led by local governments alongside a private market shared equity model, one of "bootstrapping home buying with purchase options".
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Expected utility theory (EUT) has been challenged as a descriptive theoryin many contexts. The medical decision analysis context is not an exception.Several researchers have suggested that rank dependent utility theory (RDUT)may accurately describe how people evaluate alternative medical treatments.Recent research in this domain has addressed a relevant feature of RDU models-probability weighting-but to date no direct test of this theoryhas been made. This paper provides a test of the main axiomatic differencebetween EUT and RDUT when health profiles are used as outcomes of riskytreatments. Overall, EU best described the data. However, evidence on theediting and cancellation operation hypothesized in Prospect Theory andCumulative Prospect Theory was apparent in our study. we found that RDUoutperformed EU in the presentation of the risky treatment pairs in whichthe common outcome was not obvious. The influence of framing effects onthe performance of RDU and their importance as a topic for future researchis discussed.
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Consider the problem of testing k hypotheses simultaneously. In this paper,we discuss finite and large sample theory of stepdown methods that providecontrol of the familywise error rate (FWE). In order to improve upon theBonferroni method or Holm's (1979) stepdown method, Westfall and Young(1993) make eective use of resampling to construct stepdown methods thatimplicitly estimate the dependence structure of the test statistics. However,their methods depend on an assumption called subset pivotality. The goalof this paper is to construct general stepdown methods that do not requiresuch an assumption. In order to accomplish this, we take a close look atwhat makes stepdown procedures work, and a key component is a monotonicityrequirement of critical values. By imposing such monotonicity on estimatedcritical values (which is not an assumption on the model but an assumptionon the method), it is demonstrated that the problem of constructing a validmultiple test procedure which controls the FWE can be reduced to the problemof contructing a single test which controls the usual probability of a Type 1error. This reduction allows us to draw upon an enormous resamplingliterature as a general means of test contruction.
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This chapter analyzes titling institutions and the regulation of supporting conveyancingservices. After examining the tradeoff of enforcement benefits and consent costs posed byproperty rights, it explains how different public titling systems (privacy, recording andregistration) try to solve this tradeoff, and what the consequences are for the nature andregulation of private conveyancing services. The chapter ends with a discussion of someempirical issues and data which are useful for comparing, designing and managing titlingand conveyancing systems.
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This article develops and tests a theory of the institutions that makeproperty rights viable, ensuring their enforcement, mobilizing thecollateral value of assets and promoting growth. In contrast tocontractual rights, property rights are enforced in rem, being affectedonly with the consent of the right holder. This ensures enforcement butis costly when multiple, potentially colliding rights are held in thesame asset. Different institutions reduce the cost of gathering consentsto overcome this trade-off of enforcement benefits for consent costs:recording of deeds with title insurance, registration of rights and evena regimen of purely private transactions. All three provide functionallysimilar services, but their relative performance varies with the numberof transactions, the risk of political opportunism and regulatoryconsistency. The analysis also shows the rationality of allowingcompetition in the preparation and support of private contractswhile requiring territorial monopoly in recording and registrationactivities, this to ensure independence and protect third parties.