Aktuareksamen ved Universitetet i Oslo

Abstract

It is a fact that when one is making a decision concerning the probability distribution of a random variable by means of observing this random variable, one is recommended by the statisticians to consider certain functions of the operating characteristic (O.C.) of the decision function as measures of the reliability of the actual decision made. For instance, the confidence coefficient of an interval estimator will as a rule be regarded as a measure of our confidence in the interval.     

Sons of Gwalia: defrauded shareholders' claims in insolvency

The recent Australian High Court decision in Sons of Gwalia v Margaretic abolished the rule that defrauded shareholders claims should be subordinated to the claims of general creditors in insolvency. This paper examines the decision, discusses its potential implications and explores whether it should be overruled through legislative amendment. Copyright © 2008 John Wiley & Sons, Ltd.     

Monetary and Fiscal Policy Switching

A growing body of evidence finds that policy reaction functions vary substantially over different periods in the United States. This paper explores how moving to an environment in which monetary and fiscal regimes evolve according to a Markov process can change the impacts of policy shocks. In one regime monetary policy follows the Taylor principle and taxes rise strongly with debt; in another regime the Taylor principle fails to hold and taxes are exogenous. An example shows that a unique bounded non-Ricardian equilibrium exists in this environment. A computational model illustrates that because agents' decision rules embed the probability that policies will change in the future, monetary and tax shocks always produce wealth effects. When it is possible that fiscal policy will be unresponsive to debt at times, active monetary policy (like a Taylor rule) in one regime is not sufficient to insulate the economy against tax shocks in that regime and it can have the unintended consequence of amplifying and propagating the aggregate demand effects of tax shocks. The paper also considers the implications of policy switching for two empirical issues.     

A Statistical Method for Monitoring a Change in the Rate of Nonacceptable Inpatient Claims

Abstract

This paper is an extension of earlier work (Rosenberg 1998; Rosenberg, Andrews, and Lenk 1999; Rosenberg and Griffith 2000) that introduced a statistical control model to supplement current efforts inexpensively to help reduce unnecessary expenditures. The application of the study was to predict the rate of nonacceptable inpatient claims (NACs). In that work, a statistical model was proposed to link information obtained through an expensive audit with inexpensive information that is readily available to estimate the probability that a claim is a NAC. The premise was that a statistical system can be developed to supplement the expensive audit for additional control between audits.

Estimates of the NAC rate obtained from the statistical model are used as input in a statistical monitor to assess whether the NAC rate had changed over time. The statistical monitor is the subject of this paper. The idea is that subgroups of claims can be analyzed inexpensively with the statistical monitor to determine whether any current intervention is required prior to the time of the next scheduled audit, or whether adjustments are needed in the determination of claims to be sampled for the audit. In this study, the estimate for the NAC rate at t ₀ is compared against the estimate of the NAC rate at some later time t ₁. A decision rule is proposed to assess whether a change in the NAC rate has occurred for that subgroup. The methodology is also applicable to other health care measurements.     

Mortgage timing

We study how the term structure of interest rates relates to mortgage choice at both household and aggregate levels. A simple utility framework of mortgage choice points to the long-term bond risk premium as distinct from the yield spread and the long yield as a theoretical determinant of mortgage choice: when the bond risk premium is high, fixed-rate mortgage payments are high, making adjustable-rate mortgages more attractive. We confirm empirically that the bulk of the time variation in both aggregate and loan-level mortgage choice can be explained by time variation in the bond risk premium, whether bond risk premia are measured using forecasters’ data, a vector autoregressive (VAR) term structure model, or a simple household decision rule based on adaptive expectations. The household decision rule moves in lock-step with mortgage choice, lending credibility to a theory of strategic mortgage timing by households.     

A Generalized Econometric Model and Tests of a Signalling Hypothesis with Two Discrete Signals

To test the major prediction of a signalling hypothesis-that the market price is monotonic in the signal-the price response to the signal must be measured. Since a signal is an outcome of a rational decision rule of the signaller, the market can infer the true type of the signaller from the signal. This necessitates estimation of the price response to the signal, conditional on the rational decision rule. Thus, the empirical models (e.g., event studies in corporate finance) that estimate the market price responses to signals without conditioning on the rational decision rules are misspecified if viewed as tests of the prediction of a signalling hypothesis. This paper builds a generalized econometric model with two possible discrete signals, derives the rational decision rules, presents a simple estimator of the price response to a signal, and illustrates its use in testing a recently expounded hypothesis that firms signal their true value by forcing or not forcing an outstanding convertible bond.     

Term Structure Models: A Perspective from the Long Rate

Term structure models based on dynamic asset-pricing theory are discussed by taking a perspective from the long rate. This paper partially answers two questions about the asymptotic behavior of yields on default-free zero-coupon bonds: in frictionless markets having no arbitrage, what should the behavior be; and, in known term structure models, what can the behavior be.

In frictionless markets having no arbitrage, yields of all maturities should be positive and uniformly bounded from above. The yield curve should level out as term to maturity increases. Slopes with large absolute values occur only in the early maturities. In a continuous-time framework, the longer the maturity of the yield is, the less volatile it will be. The long rate should be a nondecreasing process. Furthermore, the long rate in continuous-time factor models with nonsingular volatility matrices should be a nondecreasing deterministic function.

In the Black, Derman, and Toy model and factor models with the short rate having the mean reversion property, yields of all maturities are uniformly bounded from above. The long rate in the Duffie and Kan model with the mean reversion property is a constant. The long rate in the Heath, Jarrow, and Morton model can be infinite or a nondecreasing process. Examples with the long rate increasing are given in this paper. A model with the long rate and short rate as two state variables is then obtained.     

Optimal taxation with monopolistic competition

This paper studies optimal taxation in a Dixit–Stiglitz model of monopolistic competition. In this setting, taxes may be used as an instrument to offset distortions caused by producer markups. Since markups tend to be higher in industries where firms face less elastic demand, tax rates will be pushed lower in these industries. This tends to work against the familiar inverse elasticities intuition associated with the Ramsey tax rule. However, a key feature of the model is that the Ramsey rule responds to the industry demand curve (Chamberlin’s DD) while the monopolistic markup is a response to the demand curve faced by firms (Chamberlin’s dd). Hence, the elasticities of both these curves influence the optimal tax rate, but in opposite directions.     

Improving decision-making with scenario planning

Decision makers struggle with four important contributors to decision failure, namely, 1) bounded rationality, 2) a tendency to consider only external variables, 3) the stickiness and friction of information and knowledge, and 4) mental models that include decision premises or policies. Whether independent or combined, these decision problems can form the ultimate in decision error—folly. The four problems in decision-making are reviewed in detail and scenario planning is posited as a tool for preventing the impact of each, ultimately with an aim of avoiding folly.     

Reorganization in bankruptcy and the issue of strategic risk

The decision by creditors to force the firm into bankruptcy, where bankruptcy includes reorganization, is shown to involve the valuation of a lottery over (cooperative) games rather than a lottery over specific monetary outcomes. In the absence of assumptions about strategic (negotiating) risk, the value of creditor claims is seen to be ambiguous. This paper extends Van Horne's model of the optimal initiation of bankruptcy proceedings to include the reorganization option and strategic risk. A modified decision rule is obtained to determine the optimal solution.     

The court's power to appoint provisional liquidators to carry out rescue roles: Rethinking Legend

A dictum in a 2006 Hong Kong Court of Appeal decision had since halted the use of provisional liquidation as a restructuring device in Hong Kong, where no purpose‐built moratorium is provided, until recently, where the Court of First Instance reaffirmed the role of provisional liquidation in restructuring. The Court of First Instance (CFI) judges did so without appearing to contradict the Court of Appeal (CA) position by reconstructing the CA dictum. This paper argues that the CA dictum does not make sense in the first place and pointing out why this is so is more helpful in clarifying the governing rule than a reconstruction of CA's words, which may mislead.     

Costly participation and heterogeneous preferences in informational committees

Informational committees are groups of people who are designated to gather information. This article develops a simple model of committee size based on costly participation and preference heterogeneity. In a setting in which the information structure and policy preferences are both represented by normal random variables, I characterize an equilibrium under the mean decision rule and derive the optimal committee size. I show that when effort costs are sufficiently high, preference heterogeneity can provide members additional incentives to gather information, and thus the optimal committee size and the principal's expected payoff can increase in the heterogeneity of committee members' policy preferences.     

Science and proven experience: a Swedish variety of evidence-based medicine and a way to better risk analysis?

A key question for evidence-based medicine (EBM) is how best to model the way in which EBM should ‘[integrate] individual clinical expertise and the best external evidence’. We argue that the formulations and models available in the literature today are modest variations on a common theme and face very similar problems when it comes to risk analysis, which is here understood as a decision procedure comprising a factual assessment of risk, the risk assessment, and the decision what to do based on this assessment, the risk management. Both the early and updated models of evidence-based clinical decisions presented in the writings of Haynes, Devereaux and Guyatt assume that EBM consists of, among other things, evidence from clinical research together with information about patients’ values and clinical expertise. On this A-view, EBM describes all that goes on in a specific justifiable medical decision. There is, however, an alternative interpretation of EBM, the B-view, in which EBM describes just one component of the decision situation (a component usually based on evidence from clinical research) and in which, together with other types of evidence, EBM leads to a justifiable clincial decision but does not describe the decision itself. This B-view is inspired by a 100-years older version of EBM, a Swedish standard requiring medical decision-making, professional risk-taking and practice to be in accordance with ‘science and proven experience’ (VBE). In the paper, we outline how the Swedish concept leads to an improved understanding of the way in which scientific evidence and clinical experience can and cannot be integrated in light of EBM. How scientific evidence and clinical experience is integrated influences both the way we do risk assessment and risk management. In addition, the paper sketches the as yet unexplored historical background to VBE and EBM.     

Hedging with Two Futures Contracts: Simplicity Pays

We propose to use two futures contracts in hedging an agricultural commodity commitment to solve either the standard delta hedge or the roll‐over issue. Most current literature on dual‐hedge strategies is based on a structured model to reduce roll‐over risk and is somehow difficult to apply for agricultural futures contracts. Instead, we propose to apply a regression based model and a naive rules of thumb for dual‐hedges which are applicable for agricultural commodities. The naive dual strategy stems from the fact that in a large sample of agricultural commodities, De Ville, Dhaene and Sercu (2008) find that GARCH‐based hedges do not perform as well as OLS‐based ones and that we can avoid estimation error with such a simple rule. Our semi‐naive hedge ratios are driven from two conditions: omitting exposure to spot price and minimising the variance of the unexpected basis effects on the portfolio values. We find that, generally, (i) rebalancing helps; (ii) the two‐contract hedging rules do better than the one‐contract counterparts, even for standard delta hedges without rolling‐over; (iii) simplicity pays: the naive rules are the best one–for corn and wheat within the two‐contract group, the semi‐naive rule systematically beats the others and GARCH performs worse than OLS for either one‐contract or two‐contract hedges and for soybeans the traditional naive rule performs nearly as well as OLS. These conclusions are based on the tests on unconditional variance ( Diebold and Mariano, 1995 ) and those on conditional risk ( Giacomini and White, 2006 ).     

Improving retirement adequacy through asset class prioritization

Highly risk-averse retirees are generally advised to adopt a fixed spending strategy such as the 4% withdrawal rule. To prevent the premature depletion of a retirement portfolio, the rule attempts to proxy as the ‘safe withdrawal rate’. But a constant withdrawal rate means that retirees accumulate unspent surpluses when markets outperform and face spending shortfalls when markets underperform. While a safe withdrawal rate can prevent spending shortfalls, the opportunity cost of unspent surpluses associated with this strategy can be extreme. We apply a range of basic investment decision rules to a retirement portfolio applying various withdrawal rates and examine the probability of shortfalls over a retirement horizon. Using a block bootstrap simulation technique, we examine decision rules relating to stock and bond investments. Our results show that retirement portfolios with a bias towards stocks coupled with a decision rule that sources withdrawals from bonds and cash before stocks significantly outperforms alternative withdrawal strategies, despite the inherent increase in volatility. This finding is in direct contrast to the safe withdrawal rate conventions used in contemporary financial advice models.     

Accounting for decisions and decisions for accounting

Behavioral decision theory (BDT) is concerned with “accounting for decisions”. The development of this interdisciplinary field is traced from the appearance of several key publications in the 1950s to the present. Whereas the 1960s saw increasing theoretical and empirical work, the field really started to flourish in the 1970s with the appearance of the review by Slovic & Lichtenstein (Organizational Behavior and Human Performance, pp. 549–744, 1971), and key papers on probabilistic judgment (Tversky & Kahneman, Science, pp. 1124–1131, 1974), and choice (Kahneman & Tversky, Econometrica, pp. 263–291, 1979). From the early 1980s to the present, BDT has seen considerable consolidation and expansion and its influence now permeates many fields of enquiry. After this brief history, eight major ideas or findings are discussed. These are: (1) that judgment can be modeled; (2) bounded rationality; (3) to understand decision making, understanding the task is more important than understanding the people; (4) levels of aspiration/reference points; (5) use of heuristic rules; (6) the importance of adding; (7) search for confirmation; and (8) thought as construction. Next, comments are addressed to differences between BDT and problem solving/cognitive science. It is argued that whereas many substantive differences are artificial, two distinct communities of researchers do exist. This is followed by a discussion of some major shortcomings currently facing BDT that include questions about the robustness of findings as well as overconcern with a few specific, “paradoxial” results. On the other hand, there are many interesting issues that BDT could address and several specific suggestions are made. Moreover, these issues represent opportunities for accounting research and several are enumerated. Finally, BDT presents “decisions for accounting” in the sense that scarce resources need to be allocated to different types of research that could illuminate accounting issues. The argument is made that BDT is one research metaphor or paradigm that has proved useful in accounting and that should be supported. Such support, however, may mean that some researchers may work on issues that, at first blush, might seem distant from accounting per se.     

Behavioural normative economics: foundations,approaches and trends

This article summarises the theoretical foundations, main approaches and current trends in the field of behavioural normative economics. It identifies bounded rationality and bounded willpower as the two core concepts that have motivated the field. Since the concepts allow for individual preferences to be context-dependent and time-inconsistent, they pose an intricate problem for standard welfare analysis. The article discusses the ways in which two prominent approaches – the preference purification approach and the opportunity approach – have tackled the problem. It argues that shortcomings in each of these approaches motivate an agency-centric perspective. The article presents two concrete policy proposals of the agency-centric approach. While this approach is promising, the article argues for pluralism in normative economics since an exclusive focus on agency can likely not do justice to the multifarious concerns that citizens hold.     

The exit decision in the European venture capital market

This article analyses the exit decision in the European venture capital market, studying when to exit and how it interacts with the exit form. Using a competing risks model we study the impact on the exit decision of the characteristics of venture capital investors, of their investments and of contracting variables. Our results reveals that the hazard functions are non-monotonic for all exit forms and suggest that, in Europe, Initial Public Offering candidates take longer to be selected than trade sales. Moreover our results show that, in Europe, venture capitalists associated with financial institutions have quicker exits (stronger for trade sales), and highlight the importance of contracting variables on the exit decision. An unexpected result is that the presence on the board of directors leads to longer investment durations.     

Measuring Compliance with the Golden Rule

The golden rule of public finance is based upon the notin that intergenerational equity requires that the cost of public expenditures be spread over time in a manner that reflects the intertemporal distribution of the benefits generated by those expenditures. This is often translated into a rule that the budget be structurally balanced in accrual accounting terms. This article considers the form of accrual accounting that is most suited to the task of measuring the consistency of fiscal policy with the golden rule. It recommends a combination of the real capital maintenance approach (also known as ‘current purchasing power accounting’) and annuity depreciation. Such an approach differs from ‘current cost accounting’, which has dominated public sector models of accrual accounting in recent years. The meaning of balance-sheet measures is also considered, and it is concluded that the golden rule is more appropriately expressed as an accrual balanced budget requirement than as a requirement for the maintenance of constant net worth. JEL classification: H6, M40.     

Dynamic portfolio optimization across hidden market regimes

Regime-based asset allocation has been shown to add value over rebalancing to static weights and, in particular, reduce potential drawdowns by reacting to changes in market conditions. The predominant approach in previous studies has been to specify in advance a static decision rule for changing the allocation based on the state of financial markets or the economy. In this article, model predictive control (MPC) is used to dynamically optimize a portfolio based on forecasts of the mean and variance of financial returns from a hidden Markov model with time-varying parameters. There are computational advantages to using MPC when estimates of future returns are updated every time a new observation becomes available, since the optimal control actions are reconsidered anyway. MPC outperforms a static decision rule for changing the allocation and realizes both a higher return and a significantly lower risk than a buy-and-hold investment in various major stock market indices. This is after accounting for transaction costs, with a one-day delay in the implementation of allocation changes, and with zero-interest cash as the only alternative to the stock indices. Imposing a trading penalty that reduces the number of trades is found to increase the robustness of the approach.