Computer-Aided Teaching of Probabilistic Modeling for Biological Phenomena

College students majoring in science and engineering need to learn how to model key features of the driving mechanisms of natural, scientific, and engineering phenomena. A rigorous treatment of these topics requires a thorough understanding of advanced mathematical concepts and probability theory. However, we believe that carefully designed computer simulation software offers a means of conveying fundamental ideas of probabilistic modeling, while minimizing the need for underlying mathematical analyses. Based on this premise we have initiated the development of a software system that will be incorporated into a novel, introductory course in probabilistic modeling for undergraduate students in the biological and environmental sciences. In this paper we describe the preliminary version of our system that implements simulation, real-time animation, and calculations of dynamic statistical summaries for several prototypical stochastic models for a variety of biological systems.     

Smoothing parameter selection methods for nonparametric regression with spatially correlated errors

When spatial data are correlated, currently available data‐driven smoothing parameter selection methods for nonparametric regression will often fail to provide useful results. The authors propose a method that adjusts the generalized cross‐validation criterion for the effect of spatial correlation in the case of bivariate local polynomial regression. Their approach uses a pilot fit to the data and the estimation of a parametric covariance model. The method is easy to implement and leads to improved smoothing parameter selection, even when the covariance model is misspecified. The methodology is illustrated using water chemistry data collected in a survey of lakes in the Northeastern United States.     

Fitting disposition codes to mobile phone surveys: experiences from studies in Finland, Slovenia and the USA

Summary.  Using mobile phones to conduct survey interviews has gathered momentum recently. However, using mobile telephones in surveys poses many new challenges. One important challenge involves properly classifying final case dispositions to understand response rates and non-response error and to implement responsive survey designs. Both purposes demand accurate assessments of the outcomes of individual call attempts. By looking at actual practices across three countries, we suggest how the disposition codes of the American Association for Public Opinion Research, which have been developed for telephone surveys, can be modified to fit mobile phones. Adding an international dimension to these standard definitions will improve survey methods by making systematic comparisons across different contexts possible.     

Reference priors for constrained rate models of count data

We derive reference priors for constrained rate models of count data using the sequential algorithm of Berger and Bernardo (1992b). The event counts for various groups of subjects are modeled as discrete random variables (Poisson, binomial, or negative binomial) with group specific rates. We consider situations in which the groups can be completely ordered according to one covariate. The priors enforce monotonicity (or monotonicity and convexity) of the rates with respect to the ordering. We use the priors to model a data set on mortality rates for men in different age groups assuming that the mortality rates increase with respect to age. We also consider the situation in which the parameter space is augmented to include rates corresponding to unobserved age groups, and the case of a random upper bound on the mortality rates. In addition, we provide an evaluation of the out-of-sample predictive performance of the proposed methods.     

Italian Social Enterprises at the Crossroads: Their Role in the Evolution of the Welfare State

This paper investigates the relationship between the emergence of social enterprises (SEs) and the historical development of the Italian welfare state. Our research offers a comprehensive overview of the internal and external influences that shaped the constitutive relations between the welfare state and SEs. A qualitative methodology based on semi-structured interviews and focus groups has been adopted. This study suggests that two interconnected dynamics—the emergence of new social needs being answered by private organisations and the increased prominence of third sector actors during the privatisation of the welfare state—shaped the co-evolution of the welfare state and SEs in Italy. The study also suggests that the emergence and evolution of Social Enterprises in the years leading up to 2001 was mainly a bottom-up phenomena stemming from the actions of citizens setting up private organisations (often cooperatives) to answer to social problems created by new social needs and the structural reform of the welfare state. After 2001 especially with the new law on SEs in 2016, the evolution of SEs seems to have been increasingly influenced by the surrounding ecosystem of actors and supranational policy discourses rather than SEs themselves.     

Risk Analysis for Autonomous Underwater Vehicle Operations in Extreme Environments

Autonomous underwater vehicles (AUVs) are used increasingly to explore hazardous marine environments. Risk assessment for such complex systems is based on subjective judgment and expert knowledge as much as on hard statistics. Here, we describe the use of a risk management process tailored to AUV operations, the implementation of which requires the elicitation of expert judgment. We conducted a formal judgment elicitation process where eight world experts in AUV design and operation were asked to assign a probability of AUV loss given the emergence of each fault or incident from the vehicle's life history of 63 faults and incidents. After discussing methods of aggregation and analysis, we show how the aggregated risk estimates obtained from the expert judgments were used to create a risk model. To estimate AUV survival with mission distance, we adopted a statistical survival function based on the nonparametric Kaplan‐Meier estimator. We present theoretical formulations for the estimator, its variance, and confidence limits. We also present a numerical example where the approach is applied to estimate the probability that the Autosub3 AUV would survive a set of missions under Pine Island Glacier, Antarctica in January–March 2009.     

What are the likely interactions among innovation,government debt,and employment?

The study here analyzes the interactions among labor, R&D intensity, and public expenditure on education (indicators of innovation), considering public debt of countries. The study is based on 27 European countries over the 1995–2009 and applies multiple regression analysis. Main findings seem to be: a significant interaction of public expenditure on education and R&D intensity with employment rate, whereas an increase of general government consolidated gross debt has a negative interaction for employment rate as well as for technology indicators. The theoretical framework and empirical evidence suggest vital political economy implications to support employment rate during contractions of the business cycle. In particular, considering the specificity of the economic structure of countries, a fruitful lung-run political economy of growth should slowly dry out public debt by supporting GDP growth, rather than reducing government debt with high taxation and balanced-budget rules, in order to decrease frictional effects for patterns of economic, technological, and employment growth.     

The distribution of cook's d statistic

Cook (1977) proposed a diagnostic to quantify the impact of deleting an observation on the estimated regression coefficients of a General Linear Univariate Model (GLUM). Simulations of models with Gaussian response and predictors demonstrate that his suggestion of comparing the diagnostic to the median of the F for overall regression captures an erratically varying proportion of the values.

We describe the exact distribution of Cook's statistic for a GLUM with Gaussian predictors and response. We also present computational forms, simple approximations, and asymptotic results. A simulation supports the accuracy of the results. The methods allow accurate evaluation of a single value or the maximum value from a regression analysis. The approximations work well for a single value, but less well for the maximum. In contrast, the cut-point suggested by Cook provides widely varying tail probabilities. As with all diagnostics, the data analyst must use scientific judgment in deciding how to treat highlighted observations.     

The Failure of External Control on Public Utilities

Although on average the cost of local public services is quite high, the same cannot always be said about their quality. Why is this so? This paper suggests that the answer lies in the failure of external control systems. Specifically, four types of risk have been identified: (1) standardisation that is either lacking or incongruent; (2) inappropriate relationships between controllers and the controlled; (3) cases of erosion and resistance to control; (4) incoherence between control aims and methods, and the skill of controllers. The research method was based partly on an analysis of literature and partly on empirical observation. Initially, a thorough examination of articles on the subject published in the main international journals was carried out. Then empirical research (limited to the Italian situation) was added to support the research hypotheses, and which led to the paper’s conclusions. The results may be significant from two points of view. Firstly, although in recent years financial scandals have been very much in the news (the cases of Enron, Argentine bonds, football club scandals) literature has not yet systematically dealt with control failure. Secondly, the conclusions may be of support to public administration policy-makers or to controllers who need to improve their professionalism and diligence.