Applying neural network Poisson regression to predict cognitive score changes

In this study, we combined a Poisson regression model with neural networks (neural network Poisson regression) to relax the traditional Poisson regression assumption of linearity of the Poisson mean as a function of covariates, while including it as a special case. In four simulated examples, we found that the neural network Poisson regression improved the performance of simple Poisson regression if the Poisson mean was nonlinearly related to covariates. We also illustrated the performance of the model in predicting five-year changes in cognitive scores, in association with age and education level; we found that the proposed approach had superior accuracy to conventional linear Poisson regression. As the interpretability of the neural networks is often difficult, its combination with conventional and more readily interpretable approaches under the generalized linear model can benefit applications in biomedicine.     

Lot Splitting in Stochastic Flow Shop and Job Shop Environments*

In recent years many firms have been implementing small lot size production. Lot splitting breaks large orders into smaller transfer lots and offers the ability to move parts more quickly through the production process. This paper extends the deterministic studies by investigating various lot splitting policies in both stochastic job shop and stochastic flow shop settings using performance measures of mean flow time and the standard deviation of flow time. Using a computer simulation experiment, we found that in stochastic dynamic job shops, the number of lot splits is more important than the exact form of splitting. However, when optimal job sizes are determined for each scenario, we found a few circumstances where the implementation of a small initial split, called a “flag,” can provide measurable improvement in flow time performance. Interestingly, the vast majority of previous research indicates that methods other than equal lot splitting typically improves makespan performance. The earlier research, however, has been set in the static, deterministic flow shop environment. Thus, our results are of practical interest since they show that the specific method of lot splitting is important in only a small set of realistic environments while the choice of an appropriate number of splits is typically more important.     

National Governance Frameworks in the Global Compact on Refugees: Dangers and Opportunities

This article examines the treatment of national governance frameworks in the Global Compact on Refugees. Given that national governance frameworks are the primary determinants of whether a refugee can live safely, move freely, work, and access state and private services such as education, healthcare, banking and justice, their treatment in the Global Compact has important implications for future prospects for local integration, the durable solution least‐often discussed but most likely to become the de facto reality for most of the world's refugees.     

All The Same? On a Certain Pattern in Cross-National Death Risk

This article considers whether a nation that fares relatively well (or badly) on a particular dimension of mortality risk tends also to do so on others. Working with 2016 data from the Global Burden of Disease (GBD) Study, we focus on six causes of premature death: transport accidents, other accidents, homicide, early-childhood diseases, and both communicable and noncommunicable diseases beyond early childhood. We consider data from all 26 nations that had populations of at least 50 million in 2016, as well as 15 clusters of smaller nations that are similar in longevity (e.g., Scandinavia). We use an analytic method that facilitates useful comparisons across nations, for it recognizes that some potential death risks can be underestimated because citizens die sooner from other causes. We estimate reductions in lifespan from each of the six causes relative to natural lifespan as defined by GBD. It emerges that, for all 15 pairings among the six causes, these reductions are positively correlated. We introduce metrics to summarize a nation's overall “safety status,” and find that losses of longevity because of premature deaths are nearly three decades fewer in the safest countries than in the least safe ones. Turning to possible explanations for the cross-national differences, we find a strong association between a nation's safety status and both its economic wherewithal as indicated by the 2016 GDP per capita (adjusted for purchasing power parity) and its income inequality as reflected by its Gini coefficient.     

Logistic processes involving markovian minimization

The class of logistic processes involving geometric minimization introduced by Arnold (1989) is extended by replacing the Bernoulli sequence used in the definition of the process by a Markovian (0,1) sequence. A more flexible range of dependence structures is thus introduced. Parameter estimation and related processes are discussed.     

Estimating Gross Labor-Force Flows

We present and apply an adjustment procedure for the Bureau of the Census and Bureau of Labor Statistics gross labor-force flows data that addresses two major defects in the data. First, an adjustment procedure is developed to take account of individuals with missing labor-force classifications who are not missing at random. Second, we provide a procedure for adjustment for individuals with spurious labor-force transitions arising because of classification errors in either the current or the previous Current Population Survey. Our procedures are applied to compute adjusted monthly gross change data for the period January 1977–December 1982. The average adjustment for nonrandom missing classifications ranges from –12% to 15% of the unadjusted gross change data. The average adjustment for spurious labor-force transitions reduces estimated movements by 8%–49%. The classification adjustment also increases estimated consecutive periods of unemployment by 18%. We apply several internal and external consistency checks to our procedure. In general, the adjustments appear reasonable. We also suggest some modifications of Current Population Survey procedures that could reduce the use of ex post adjustment procedures in the future.     

Identifying Different Areas of Inhomogenous Mineral Subsoil: Spatial Fluctuation Approaches

We use a recently proposed fluctuation-type procedure for detecting breaks in spatial regions to distinguish between hard and soft areas of inhomogeneous mineral subsoil like additives, air pockets, and adhesion. For a proper application, some refinements of the procedure are necessary. Both simulation evidence of the refinement and the application on the subsoil yield favorable results.     

GROWTH OPPORTUNITIES,STRATEGIC SAVINGS,AND THE DOT‐COM BOOM AND BUST

Data from the dot‐com boom‐bust episode suggest that growth opportunities played an important role in explaining firms' financing strategy during this understudied episode. The low leverage of this sector was mainly driven by high growth firms which increased their leverage following the crash despite suffering a much larger fall in their market value. We present a parsimonious dynamic firm financing model where growth opportunities alone can generate the heterogeneous patterns in the financing and performance between high and low growth information technology firms prior to and following the market crash. The calibrated model also sheds light on the role played by monetary policy during that episode. (JEL G32, E22, E5)