Arto Luoma

Pitman Nearness, Distance Criterion and Optimal Regression Designs:

Pitman Nearness is a criterion for point estimation while the Distance Criterion is an optimality criterion. There is indeed a striking similarity between the two. In this paper we will present a variety of basic results towards estimation and ⁄ or prediction in the context of a regression model , based on the distance criterion .

Modelling the general public's inflation expectations using the Michigan survey data

In this article we discuss a few models developed to explain the general publics inflation expectations formation and provide some relevant estimation results. Furthermore, we suggest a simple Bayesian learning model which could explain the expectations formation process on the individual level. When the model is aggregated to the population level it could explain not only the mean values, but also the variance of the publics inflation expectations. The estimation results of the mean and variance equations seem to be consistent with the results of the questionnaire studies in which the respondents were asked to report their thoughts and opinions about inflation.

A Bayesian smoothing spline method for mortality modelling

Abstract We propose a new method for two-dimensional mortality modelling. Our approach smoothes the data set in the dimensions of cohort and age using Bayesian smoothing splines. The method allows the data set to be imbalanced, since more recent cohorts have fewer observations. We suggest an initial model for observed death rates, and an improved model which deals with the numbers of deaths directly. Unobserved death rates are estimated by smoothing the data with a suitable prior distribution. To assess the fit and plausibility of our models we perform model checks by introducing appropriate test quantities. We show that our final model fulfils nearly all requirements set for a good mortality model.

Optimal Designs in Random Coefficient Linear Regression Models

In this paper we consider a random coefficients regression model in the context of repeated measurements. The measurements are taken at consecutive points for several experimental units, and the total number of measurements have a fixed upper bound. Observations on the same unit at different points will be correlated while observations on two differents units are uncorrelated. We present optimal designs for slope parameter estimation and prediction.

ANTERIOR CHAMBER FLARE DURING BEVACIZUMAB TREATMENT IN EYES WITH EXUDATIVE AGE-RELATED MACULAR DEGENERATION.

Purpose: To study the anterior chamber flare during bevacizumab treatment of exudative age-related macular degeneration. Methods: During a 2-year prospective follow-up, 50 patients recently diagnosed with exudative age-related macular degeneration were treated at once-a-month visits if subretinal or intraretinal fluid or a new hemorrhage was present in the lesion area. Flare was measured weekly during the first month and then monthly in both eyes. Results: Higher flare was associated with older age (P = 0.007, Linear Mixed Model), higher number of smoking pack-years (P = 0.019), macular cysts (P = 0.041), and pseudophakia (P = 0.003). The levels gradually increased during the follow-up (P < 0.0001) but less in the eyes with classic CNV (P = 0.011). Flare decreased during treatment-free periods lasting for at least two consecutive visits (P = 0.005). A peak in flare was observed 1 week after the first injection (P = 0.034, Wilcoxon signed rank test). In the fellow eyes, higher flare values in the beginning of the follow-up were associated with later conversion into exudative age-related macular degeneration (P = 0.015, Mann–Whitney U test). Conclusion: Anterior chamber flare correlated poorly with the CNV activity. Higher levels may, however, precede or exist early in the process that leads to the development of exudative age-related macular degeneration.

Bayesian two-stage regression with parametric heteroscedasticity

In this paper, we expand Kleibergen and Zivots (2003) Bayesian two-stage (B2S) model by allowing for unequal variances. Our choice for modeling heteroscedasticity is a fully Bayesian parametric approach. As an application, we present a cross-country Cobb–Douglas production function estimation.

Environment Modelling in Closed Specifications of Embedded Systems

An embedded system is in constant interaction with its environment. It can consist of several, possibly distributed, components communicating with each other using interfaces. Collective behaviour between the system and its environment may be nondeterministic or random, and can include continuous quantities. The effects of the collective behaviour to the architecture of the system are non-obvious and should be considered before defining the interfaces between system components. This calls for methods capable of expressing complex collective behaviour and providing proper structuring of complex specifications. In this paper we discuss such capabilities in conjunction with the DisCo method.

Atypical physiological orienting to direct gaze in low‐functioning children with autism spectrum disorder

Reduced use of eye contact is a prominent feature in individuals with autism spectrum disorder (ASD). It has been proposed that direct gaze does not capture the attention of individuals with ASD. Experimental evidence is, however, mainly restricted to relatively high‐functioning school‐aged children or adults with ASD. This study investigated whether 2–5‐year‐old low‐functioning children with severe ASD differ from control children in orienting to gaze stimuli, as measured with the heart rate deceleration response. Responses were measured to computerized presentations of dynamic shifts of gaze direction either toward (direct) or away (averted) from the observing child. The results showed a significant group by gaze direction interaction effect on heart rate responses (permuted P = .004), reflecting a stronger orienting response to direct versus averted gaze in typically developing (N = 17) and developmentally delayed (N = 16) children but not in children with ASD (N = 12). The lack of enhanced orienting response to direct gaze in the ASD group was not caused by a lack of looking at the eye region, as confirmed by eye tracking. The results suggest that direct gaze is not a socially salient, attention‐grabbing signal for low‐functioning children with ASD. Autism Res 2017, 10: 810–820.

Bayesian analysis of equity-linked savings contracts with American-style options

In this paper, a full Bayesian procedure is developed and implemented for the market consistent valuation of a fairly general class of equity-linked savings contracts. The developed procedure allows several combinations of contract properties. For example, the contract returns may include a guaranteed interest rate and a bonus depending on the yield of a total return equity index. Especially, the contract may include an American-style path-dependent surrender option. The underlying asset and interest rate processes are estimated using the Markov chain Monte Carlo method, and their simulation is based on their posterior predictive distribution, which is, however, adjusted to give risk-neutral dynamics. Financial guarantees and equity-linked components are common in many life insurance products. From the insurance company’s viewpoint, this paper provides a realistic and flexible modelling tool for product design and risk analysis. The focus is on a novel application of advanced theoretical and computational methods, which enable us to deal with a fairly realistic valuation framework and to address model and parameter error issues. Our empirical results support the use of elaborated instead of stylized models for asset dynamics in practical applications.