Stochastic Models of Implied Volatility Surfaces

We propose a market–based approach to the modelling of implied volatility, in which the implied volatility surface is directly used as the state variable to describe the joint evolution of market prices of options and their underlying asset. We model the evolution of an implied volatility surface by representing it as a randomly fluctuating surface driven by a finite number of orthogonal random factors. Our approach is based on a Karhunen–Loeve decomposition of the daily variations of implied volatilities obtained from market data on SP500 and DAX options.
We illustrate how this approach extends and improves the accuracy of the well–known 'sticky moneyness' rule used by option traders for updating implied volatilities. Our approach gives a justification for the use of 'Vegas' for measuring volatility risk and provides a decomposition of volatility risk as a sum of independent contributions from empirically identifiable factors.
(J.E.L.: G130, C14, C31).     

Output gap in Brazil: a real-time data analysis

Recent literature for developed economies has shown that output gap estimates go through important revisions over time, impairing their reliability in real time. We organize a real-time data set for Brazil’s GDP and assess the revisions of the output gap estimated by four different methods. Similar to the findings of studies for developed economies, the output gap revisions in Brazil are substantial in all methods, with frequent changes in the output gap sign. In general, both the GDP data revision and the effect of adding new observations to the sample are relevant sources of output gap revisions. However, differently from those studies, we cannot assert that the latter source is preponderant.     

Patterns of care and burden of chronic idiopathic thrombocytopenic purpura in Brazil

Aims: Although several therapeutic options are available for chronic immune thrombocytopenic purpura (cITP), little is known about the treatment of cITP in Brazil.

Materials and methods: A multi-center, retrospective chart review, observational study was designed to describe the treatment patterns, clinical burden, resources use, and associated costs for adult patients diagnosed with cITP and treated in public and private institutions in Brazil. Patient charts were screened in reverse chronological order based on their last visit post January 1, 2012. (All costs were calculated using 1.00 USD?=?3.9571 BRL, from February 2016.)

Results: Of 340 patient charts screened, 50 patients were eligible for inclusion in the study. Single-drug therapy (prednisone, dexamethasone, or dapsone) was the most commonly used treatment, followed by combination therapies (azathioprine?+?prednisone, azathioprine?+?prednisone?+?danazol, and prednisone?+?dapsone). Splenectomy was performed in 22% of patients after at least first-line treatment. Platelet count and number of bleeding episodes at diagnosis were 31,561.1/mm³ (SD?=?±26,396.1) and 40 episodes, respectively; in first-line, 92,631.1/mm³ (SD?=?±79,955.3) and 19 episodes, respectively; in second-line, 96,950.0/mm³ (SD?=?±76,476.4) and 17 episodes, respectively. Private system patients had a higher median cost compared to public system patients (USD 17.49/month, range?=?0–2,020.77 vs USD 9.51/month, range?=?0–192.64, respectively).

Limitations: This study does not allow conclusions for causal explanations due to the cohort study design, and treatment patterns represent only the practices of physicians who have agreed to participate in the study.

Conclusions: The data indicate that available therapeutic strategies for second- and third-line therapies appear to be limited.     

From disruptions to struggles: Theorizing power in ERP implementation projects

Enterprise resource planning (ERP) implementation projects often fail to achieve their objectives. These often problematic projects are frequently the setting for intense and growing power struggles. Existing studies (e.g., Boonstra, 2006; Shepherd, Clegg, & Stride, 2009) have provided researchers with insights about issues of power in these projects. However, existing research has yet to provide a comprehensive picture of power in these projects or insights on how this picture changes with the passage of time. Clegg's (1989) circuits of power framework provides a useful tool for developing this needed comprehensive picture. We use the circuits of power framework as a tool for categorizing existing literature on power in ERP implementations. More importantly, we draw on this framework to provide a comprehensive view of power in the particular context of these projects. Specifically, we analyze the power relations during the implementation of an ERP in an organization. We do so by identifying how disturbances to the circuits of power – power struggles – arise and intensify during the implementation of the ERP. In this way, our work makes both a theoretical and an empirical contribution to the study of power in ERP implementation projects.     

The meta-crisis of secular capitalism

The current global economic crisis concerns the way in which contemporary capitalism has turned to financialisation as a double cure for both a falling rate of profit and a deficiency of demand. Although this turning is by no means unprecedented, policies of financialisation have depressed demand (in part as a result of the long-term stagnation of average wages) while at the same time not proving adequate to restore profits and growth. This paper argues that the current crisis is less the ‘normal’ one that has to do with a constitutive need to balance growth of abstract wealth with demand for concrete commodities. Rather, it marks a meta-crisis of capitalism that is to do with the difficulties of sustaining abstract growth as such. This meta-crisis is the tendency at once to abstract from the real economy of productive activities and to reduce everything to its bare materiality. By contrast with a market economy that binds material value to symbolic meaning, a capitalist economy tends to separate matter from symbol and reduce materiality to calculable numbers representing ‘wealth’. Such a conception of wealth rests on the aggregation of abstract numbers that cuts out all the relational goods and the ‘commons’ on which shared prosperity depends.     

Enticing the Stork: Can we Evaluate Pro‐Natal Policies Before Having Children?

Aside from immigration, the only meaningful demographic lever available to policymakers attempting to moderate the rate of ageing is the birth rate. This article departs from previous analyses of pro‐natal policies by studying determinants of pro‐natal options ex ante, which represents an advantage for policymakers looking to craft policies with prior knowledge of whether or not a demographic policy will have a significant effect. Our multinomial regression model for a US sample involving college students shows that the preferred choice of pro‐natal incentive is dependent on gender, economic class, number of planned children and migrant status. We find that females are more likely than males to choose any pro‐natal incentive over no incentive. The highest odds for increasing planned number of children are for maternity leave and parental leave options. Respondents associating themselves with the poorest economic class are more likely to choose daycare or government grant as pro‐natal options.     

Understanding the microenterprise sector to design a tailor-made microfinance policy for Cape Verde

Two of the central challenges faced by Cape Verde at the present are the high level of unemployment and the increasing proportion of the population living in (relative) poverty. Microenterprise development can be an effective means of addressing both problems in a developing country like Cape Verde, where microenterprises account for about 50% of employment. In this paper we provide a detailed profile of Cape Verdean microenterprises and microentrepreneurs and investigate the relationship between their characteristics and the resort to outside seed capital. We find a cluster of factors—the microentrepreneur’s age, gender, level of education and reason for being self-employed—which influence significantly the probability of being in need for external start-up capital. The policy implications of these findings for the design of a specific microfinance program for Cape Verde are discussed.

Forecasting UK consumer price inflation using inflation forecasts

The inflation rate is a key economic indicator for which forecasters are constantly seeking to improve the accuracy of predictions, so as to enable better macroeconomic decision making. Presented in this paper is a novel approach which seeks to exploit auxiliary information contained within inflation forecasts for developing a new and improved forecast for inflation by modeling with Multivariate Singular Spectrum Analysis (MSSA). Unlike other forecast combination techniques, the key feature of the proposed approach is its use of forecasts, i.e. data into the future, within the modeling process and extracting auxiliary information for generating a new and improved forecast. We consider real data on consumer price inflation in UK, obtained via the Office for National Statistics. A variety of parametric and nonparametric models are then used to generate univariate forecasts of inflation. Thereafter, the best univariate forecast is considered as auxiliary information within the MSSA model alongside historical data for UK consumer price inflation, and a new multivariate forecast is generated. We find compelling evidence which shows the benefits of the proposed approach at generating more accurate medium to long term inflation forecasts for UK in relation to the competing models. Finally, through the discussion, we also consider Google Trends forecasts for inflation within the proposed framework.     

Finding Closest Targets in Non-Oriented DEA Models: The Case of Convex and Non-Convex Technologies

This paper draws attention for the fact that traditional Data Envelopment Analysis (DEA) models do not provide the closest possible targets (or peers) to inefficient units, and presents a procedure to obtain such targets.It focuses on non-oriented efficiency measures (which assume that production units are able to control, and thus change, inputs and outputs simultaneously) both measured in relation to a Free Disposal Hull (FDH) technology and in relation to a convex technology. The approaches developed for finding close targets are applied to a sample of Portuguese bank branches.