Certainty Case Research Articles

Applicability of selected Brighton Collaboration case definitions in low-resource settings: A prospective hospital-based active surveillance in Addis Ababa, Ethiopia

IntroductionStandardizing case definitions for priority vaccine safety conditions facilitates uniform evaluation and consolidation of data obtained from different settings. The Brighton Collaboration case definitions (BCCD) were created to support this harmonization and enable classification from level 1 (most certain) to level 5 (not a case) of certainty. Assessing the performance of BCCD in practice is critical, particularly in resource-limited settings, where many new vaccines may be introduced without prior monitoring in high-income countries. We assessed the performance of BCCD in Addis Ababa, Ethiopia, as applicable to COVID-19 and other vaccines. MethodsActive surveillance was conducted at Tikur Anbessa Specialized Hospital, the largest referral hospital in Ethiopia. During June 1, 2022–May 31, 2023, three trained physicians prospectively identified patients eligible for COVID-19 vaccination (regardless of vaccine receipt) who presented with one or more of eleven pre-specified adverse events of special interest (AESI) from the emergency department and inpatient wards. Standardized data collection forms were used to capture patient information and assign level of certainty (LOC), regardless of vaccination status for COVID-19. We conducted descriptive analysis to characterize cases and the LOCs reached for each AESI. ResultsWe detected 203 AESI cases. The most detected conditions were thrombosis and thromboembolism (n = 100, 49 %) and generalized convulsions (n = 38, 19 %). Ninety-six percent of the cases were confirmed at levels 1–3 (n = 187) or level 5 (n = 9) LOC. Non-classifiable (level 4) cases were observed for pericarditis (n = 2), encephalitis (n = 2), myelitis (n = 2), and generalized convulsion (n = 1). ConclusionThe BCCD were successfully applied in > 95 % of cases in a large referral hospital in Ethiopia, with generalized convulsion, pericarditis, and encephalomyelitis as the exceptions. We recommend further evaluation in other low-resource settings, particularly in rural or non-referral hospitals, to gain additional insights into performance of these definitions for revision or adaptation, as needed.

Optimal consumption for recursive preferences with local substitution — the case of certainty

We characterize optimal consumption policies in a recursive intertemporal utility framework with local substitution. We establish existence, uniqueness, and a version of the Kuhn–Tucker theorem. The structure of optimal consumption plans is described explicitly for a large class of aggregators. For Epstein-Zin preferences, the solution coincides with the solution of the corresponding time-additive preferences.

Active timber management by outsourcing stumpage price uncertainty with the American put option

Timber production is risky, with price uncertainties caused by stumpage price fluctuations. In this study, the American put option is employed to outsource such uncertainty and establish the reservation prices at various stand ages. Put option values and the reservation prices derived thereof, thus, help forestland owners decide whether the stumpage price is high enough to justify an immediate timber harvest. With a series of simulations, we demonstrated that using an American put option to cover the downside price risk could substantially increase the average land expectation value compared to the certainty case. Besides, the simulations confirm that buying an American option as a price insurance would deduct land expectation values compared to the methods proposed by Brazee and Mendelsohn. In addition, we proposed a rolling put option method that allows forestland owners to buy partial length put options to balance their cost and price uncertainty protection. Overall, with the help of American put option, forestland owners for the first time could actively make their harvest decisions from the price setter perspective instead of being pure market price taker like they have been since the beginning of commercial forestry.

Day-ahead optimal scheduling of a standalone solar-wind-gas based integrated energy system with and without considering thermal inertia and user comfort

Integrated energy system is an effective way to utilize renewable energy in a high proportion and reduce carbon emissions. However, renewable energy and load uncertainties bring great challenges to the optimal operation of the integrated energy system. The standalone integrated energy system shows the characteristics of excessive dependence on energy storage for the lack of large power grid support. To reduce the energy storage dependency and improve the scheduling optimization performance of the system, a standalone solar-wind-gas based integrated energy system (SWG-IES) is used to explore the relationship between uncertainties, thermal inertia and user comfort. Based on the characteristics of SWG-IES, day-ahead scheduling models with and without considering thermal inertia and user comfort are proposed. The optimization calculation and comparative analysis of four cases are carried out. Simulation results show thermal inertia and user comfort have significant impacts on day-ahead optimization strategy. After considering thermal inertia and user comfort, the utilization ratio of the battery and heat storage tank decreased by about 75 % and 30 % respectively, and abandoned heat occurred in certainty case. The function of thermal inertia and user comfort is equivalent to increasing the capacity of energy storage in the system, which has a positive impact on the large-scale and high-proportion use of renewable energy.

The Case of Legal Certainty, an Uncertain Transplant Process in France

The reception of the fundamental principle of legal certainty in France shows how the characteristics of the French administrative system have consequences for the development and consideration of this principle. An analysis of the transplantation process reveals that it has been largely prepared, knowingly or unknowingly, to allow the principle of legal certainty to find at least a partial place in the French administrative system. It also shows the central role of the administrative judge in this process which led to the adaptation of the principle of legal certainty to the French legal order, and vice versa.

Optimal Robust Monetary Policy with Parameters and Output Gap Uncertainty

This paper studies optimal robust monetary policy when the central bank imperfectly observes potential output and has Knightian uncertainty about the intertemporal elasticity of substitution and the slope of the Phillips curve. The literature on optimal robust monetary policy has focused on either imperfect observability of some variables or on parameter uncertainty. We characterize robust monetary policy analytically under the two types of uncertainty and show that in general they call for a more aggressive reaction of monetary policy compared with the certainty case.

The 'Uncertainty' Fraud: Joan Robinson, G. L. S. Shackle and Paul Davidson's Sleight of Hand Change of Keynes's Uncertainty Definition in the General Theory

J. M. Keynes gave an exact and precise definition of his concept of uncertainty in the General Theory. Keynes stated that uncertainty was an inverse function of the weight of the evidence on page 148 of chapter 12 of the General Theory. The weight of the evidence concept was carefully discussed and modeled by Keynes in chapters 6 and 26 of the A Treatise on Probability. The fundamentalist Keynesians, such as Joan Robinson, G. L. S. Shackle and Paul Davidson, had no idea about what Keynes was talking about because none of them had the academic training in mathematics and logic that would have enabled them to understand what the weight of the evidence, w, is or how it is different from the Evidential Weight of the Argument, V. Robinson, Shackle and Davidson then resorted to a sleight of hand. They claimed Keynes had changed his mind about the definition and meaning of uncertainty in his 1937 Quarterly Journal of Economics reply to mean “we simply do not know”, rather than uncertainty being an inverse function of the weight of the evidence as defined on p.148 of the General Theory in chapter 12. The change is monumental because it changes the meaning of uncertainty from being a range, defined on the interval between 0 and 1,0 ≤ w ≤ 1, where w is the weight of the evidence, to being w=0, which is the case of complete ignorance. The terms radical, fundamental, and irreducible uncertainty mean total and compete ignorance. This sets up the Shackleian claim that either you know everything, which is the case of certainty or certain knowledge, or you know nothing, which is his case of uncertainty or no knowledge, because “un” mean no. There is nothing in between. There are no gradations or degrees of uncertainty. This sleight of hand is the “uncertainty” fraud. It leads to the rejection of Keynes’s IS-LP(LM) model in chapters 15 and 21 of the General Theory, based on the claim that the existence of pervasive radical, fundamental, irreducible uncertainty makes any kind of formal logical, statistical, probabilistic, or mathematical modeling impossible. It is easy to show that Keynes never changed his mind about the definition of uncertainty in his 1937 Quarterly Journal of Economics reply because he continues to insist that there are degrees of uncertainty and that the neoclassical model of the rate of interest is incorrect because there is one equation missing from their model-the Liquidity preference function that Robinson, Shackle, and Davidson claim did not exist. The Uncertainty Fraud is the foundation for the Post Keynesian School of economics.

Social Preference and Social Welfare Under Risk and Uncertainty

This handbook chapter covers the existing theoretical literature on social preference and social welfare under risk (i.e., when probability values enter the data of the situation) and uncertainty (i.e., when this is not the case and only subjective probability assessments can be formed). Section 1 sets the stage historically by contrasting classical social choice theory and welfare economics, which are restricted to the certainty case, with Harsanyi's pathbreaking attempt at extending these fields to the risk case. Section 2 reviews the work, both ancient and recent, stemming from Harsanyi's Impartial Observer Theorem. Section 3 does the same job for Harsanyi's Social Aggregation Theorem and discusses Sen's objections against the utilitarian relevance of either theorem. Section 4 explains why the Social Aggregation Theorem does not carry through from risk to uncertainty, a major conundrum that can also be expressed as a clash between ex ante and ex post welfare assessments; the proposed solutions are covered, including some very recent ones. Section 5 explains that equality, like social welfare, can be defined either ex ante or ex post, and using a basic example by Diamond, that these two definitions clash with each other. Section 6 covers the main solutions that egalitarian writers have given to this problem, again including some very recent ones.

Prospect Theory and Two Moment Model: The Firm Under Price Uncertainty

Within the prospect theory the paper examines production and hedging decisions of a competitive firm under price uncertainty. We consider the prospect theory for the firm's utility function in the two moment model known as (mu,sigma)-preference. In contrast to the literature our findings show that the production under uncertainty can be larger than in the certainty case. Furthermore, we demonstrate that although the futures markets are unbiased the firm is overhedging.

Faith in science.

It is argued that there is a lot of faith required to believe scientific truths as well as religious truths. The author notes that science is based on observation. So is religion. Scientific observation these days is based on techniques so sophisticated that one has no hope of ever seeing these things for oneself, so one is left believing the words of others who say that they have seen them. As science proceeds from hypothesis through observation and refinement to almost indisputable fact, the requisite faith necessary for acceptance declines and certainty in the belief expands. Nevertheless, it is questionable whether this is a case of certainty or just familiarity. Religious beliefs are also based on observations seen by others who claim miraculous experiences. In this way, there seems to be very little difference between the faith necessary to form beliefs in science and religion. He concludes that there is an element of remoteness in parts of science that requires believing what others tell us rather than experiencing it ourselves. This, it seems to him, is faith.

Robust delegation with uncertain monetary policy preferences

Recent research has renewed interest in the exploration of the optimal design of monetary policy institutions in the presence of uncertainty. In this paper, we revisit the rationale for delegation to a weight-conservative central banker when the social planner's knowledge about the true preferences of delegates is ex ante ambiguous and he exhibits a preference for robustness. In this context, a robust (worst-case oriented) delegation strategy is intended to minimize the maximum welfare loss over the uncertainty set, when no prior probability distribution for the preference bias is available. We find that both effective over- and underconservatism may emerge with respect to the certainty case, for robust delegation is shown to be model-dependent. Most importantly, under reasonable model's parameterizations, Rogoff's principle is reversed: it is optimal for society to appoint a weight-liberal central banker.

A Case of Doubtful Certainty: The Court Relapses into Search Incident to Arrest Confusion in Arizona v. Gant

A Case of Doubtful Certainty: The Court Relapses into Search Incident to Arrest Confusion in Arizona v. Gant

Uncertainty and the double dividend hypothesis

ABSTRACTThis paper examines the double dividend hypothesis in the presence of labour income uncertainty. Empirical evidence shows that uncertainty over labour income is particularly significant in developing, while not negligible in developed countries. Under uncertainty, and assuming incomplete capital markets, the tax system plays a role in providing social insurance, and a green tax reform influences its effectiveness. We show that the increase in environmental tax reduces consumption risk, while the balanced budget decrease in labour income tax increases income risk. We find that the total welfare effect of a green tax reform differs substantially from the case of certainty. The critical parameters determining the existence of a second dividend are the lump-sum transfers, the relative substitutability of the two goods for leisure, and the initial tax rates relative to their optimal that determine also the response of labour supply to a change in the tax mix.

An Interpretation of the Collapsing Process of the Bretton Woods System

This paper attempts to determine the environments that market confidence might play a significant role in the collapse of the Bretton Woods system. We build a game-theoretic model of currency crises where a continuum of small speculators can decide their market confidence and trading positions. In the model, the convertibility of dollar is assumed to exhibit a long-term downtrend due to Triffin’s dilemma. The problem is analyzed on the grounds of both certainty and uncertainty. In the certainty case, we find that if the convertibility of dollar is low enough, a dollar crisis is inevitable, but if the convertibility is in an intermediate range with multiple equilibria, the Bretton Woods system is vulnerable to self-fulfilling speculation. In the uncertainty case, the incidence of the confidence crises will disproportionately increase as the convertibility of dollar falls. Lastly, this paper shows that the Federal Reserve Bank’s secrecy may extend the maximum lifespan of the Bretton Woods system.

Uncertainty and the Double Dividend Hypothesis

This paper examines the double dividend hypothesis in the presence of labour income uncertainty. Empirical evidence shows that uncertainty over labour income is particularly significant in developing, while not negligible in developed countries. Under uncertainty, and assuming incomplete capital markets, the tax system plays a role in providing social insurance and a green tax reform influences its effectiveness. We show that the increase in environmental tax reduces consumption risk while the balanced budget decrease in labour income tax increases income risk. We find that the total welfare effect of a green tax reform differs substantially from the case of certainty. The critical parameters determining the existence of a second dividend are the lump sum transfers, the relative substitutability of the two goods for leisure and the initial tax rates relative to their optimal that determine also the response of labour supply to a change in the tax mix.

Selection and evaluation of projects to conserve ecosystem services

Climate and land use changes are reducing ecosystem services. Ecosystem managers can alleviate such adverse impacts by being more efficient in allocating limited budgets to projects designed to conserve ecosystem services, and ensuring that implemented projects are effective in stemming losses in ecosystem services. A conceptual framework is developed that managers can use for this purpose. The framework consists of two elements: (1) an a priori optimization model for selecting projects that minimize present value loss in ecosystem services subject to a budget constraint; and (2) an a posteriori model for determining the extent to which implemented projects have decreased ecosystem losses. An optimization model is formulated for three cases, which assume the ecosystem manager: (1) knows for sure how project expenditures influence losses in ecosystem services (certainty case); (2) does not know for sure how project expenditures influence losses in ecosystem services, but is able to specify the probabilities of service losses for different projects (risk case); and (3) is uncertain how project expenditures influence losses in ecosystem services (uncertainty case). Efficient selection of projects is evaluated for two areas of an ecosystem in mathematical and graphical terms using a continuous negative exponential relationship between present value losses and project expenditures for the certainty case, and for five expenditure classes in the risk and uncertainty cases. Two versions of the certainty case are evaluated, weak sustainability and strong sustainability. Weak sustainability allows gains in one ecosystem service to compensate for losses in another ecosystem service; strong sustainability does not. The risk case requires the manager to specify the conditional probabilities for present value losses given project expenditures, and utilizes expected costs and expected budget amounts in the budget constraint. It is solved by allocating the budget among projects so as to equalize the expected marginal present value losses in ecosystem services across projects. The uncertainty case requires the manager to specify ecosystem sustainability states and the present value losses in ecosystem services for combinations of states and projects. It is solved by selecting projects that minimize the maximum present value loss in ecosystem services subject to the budget constraint. The a posteriori evaluation method uses Bayesian statistical inference to test hypotheses about the extent to which implemented projects reduce losses in ecosystem services. It requires specifying ecosystem states that describe conditions for ecosystem services, and decides which hypothesis is true based on posterior probabilities of ecosystem states.

On the satisfaction of peak demand in the certainty case

The concept of full-capacity flat-rate equilibrium is explored for a version of the Arrow-Debreu model with time-differentiated goods and production subject to a capacity constraint. The corresponding equilibrium allocations are shown to be inefficient in general. It is also shown that rationing peak demand is Pareto superior to non-rationing.

Strategy-proof risk sharing

We consider risk sharing problems with a single good and a finite number of states. Agents have a common prior and their preferences are represented in the expected utility form and are risk averse. We study efficient and individually rational risk sharing rules satisfying strategy-proofness, the requirement that no one can ever benefit by misrepresenting his preference. When aggregate certainty holds, we show that “fixed price selections” from Walrasian correspondence are the only rules satisfying efficiency, individual rationality, and strategy-proofness. However, when aggregate uncertainty holds, we show that there exists no rule satisfying the three requirements. Moreover, in the two agents case, we show that dictatorial rules are the only efficient and strategy-proof rules. Dropping the common prior assumption in the model, we show that this assumption is necessary and sufficient for the existence of rules satisfying the three main requirements in the two agents and aggregate certainty case.

Intertemporal Price Cap Regulation Under Uncertainty

This paper examines the intertemporal price cap regulation of a firm that has market power. Under uncertainty, the unconstrained firm ‘waits longer’ before investing or adding to capacity and as a corollary, enjoys higher prices over time than would be observed in an equivalent competitive industry. In the certainty case, the imposition of an inter‐temporal price cap can be used to realise the competitive market solution; by contrast, under uncertainty, it cannot. Even if the price cap is optimally chosen, under uncertainty, the monopoly firm will generally (a) under‐invest and (b) impose quantity rationing on its customers.

EXISTENCE CONDITIONS OF THE OPTIMAL STOPPING TIME : THE CASES OF GEOMETRIC BROWNIAN MOTION AND ARITHMETIC BROWNIAN MOTION

A type of optimal investment problem can be regarded as an optimal stopping problem in the field of applied stochastic analysis. This study derives the existence conditions of the optimal stopping time when the stochastic process is a geometric Brownian motion or an arithmetic Brownian motion. The conditions concern the intrinsic value function and are natural extensions of the certainty case. Additionally, they are essential for a well-known result in recent investment theory. They are also applied to an optimal land development problem. The analyses give existing studies rigorous foundations and generalize them.