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Models based on species distributions are widely used and serve important purposes in ecology, biogeography and conservation. Their continuous predictions of environmental suitability are commonly converted into a binary classification of predicted (or potential) presences and absences, whose accuracy is then evaluated through a number of measures that have been the subject of recent reviews. We propose four additional measures that analyse observation-prediction mismatch from a different angle – namely, from the perspective of the predicted rather than the observed area – and add to the existing toolset of model evaluation methods. We explain how these measures can complete the view provided by the existing measures, allowing further insights into distribution model predictions. We also describe how they can be particularly useful when using models to forecast the spread of diseases or of invasive species and to predict modifications in species' distributions under climate and land-use change.

The simplest and the most commonly used measure for assess the classification model quality is parameter Q2 = 100 (p + n) / N (%) named the classification accuracy, p, n and N are the total numbers of correctly predicted compounds in the first and in the second class, and the total number of elements of classes (compounds) in data set, respectively. Moreover, the most probable accuracy that can be obtained by a random model is calculated for two-state model by the formulae Q2,rnd = 100 [(p + u) (p + o) + (n + u) (n + o)] / N2 (%), where u and o are the total number of under-predictions (when class 1 is predicted by the model as class 2) and over-predictions (when class 2 is predicted by the model as class 1) in data set, respectively. Finally, the difference between these two parameter ΔQ2 = Q2 – Q2,rnd is introduced, and it is suggested to compute and give ΔQ2 for each two-state classification model to assess its contribution over the accuracy of the corresponding random model. When data set is ideally balanced having the same numbers of elements in both classes, the two-state classification problem is the most difficult with maximal Q2 = 100 % and Q2,rnd = 50 %, giving the maximal ΔQ2 = 50 %. The usefulness of ΔQ2 parameter is illustrated in comparative analysis on two-class classification models from literature for prediction of secondary structure of membrane proteins and on several quanti¬tative structure-property models. Real contributions of these models over the random level of accuracy is calculated, and their ΔQ2 values are compared mutually and with the value of ΔQ2 (= 50 %) for the most difficult two-state classification model.

This study examines whether the characteristics of risk classification are effective by developing different models to predict claim occurrences. We use three unique types (Form A, Form B, and Form C) of coverage for vehicle damage insurance data in Taiwan. We first identify the basic characteristics of policyholders and vehicles which are currently applied by insurers for property damage to vehicles. We further investigate some supplementary information, which requires small information cost for the insurers to obtain from the insureds. Our evidence shows that, for the crucial risk classification based on the current official rating formula, claim coefficient is a relatively critical factor for Form A, while claim coefficient and car age are important for Form B, and policyholder age is important for Form C. We also find that some additional information such as the claim record in the previous policy year provides useful information for risk classification. Our findings imply that the official rating formula

As the cost of storing, sharing, and analyzing data has decreased, economic activity has become increasingly digital. But while the effects of digital technology and improved digital communication have been explored in a variety of contexts, the impact on economic activity—from consumer and entrepreneurial behavior to the ways in which governments determine policy—is less well understood. Economic Analysis of the Digital Economy explores the economic impact of digitization, with each chapter identifying a promising new area of research. The Internet is one of the key drivers of growth in digital communication, and the first set of chapters discusses basic supply-and-demand factors related to access. Later chapters discuss new opportunities and challenges created by digital technology and describe some of the most pressing policy issues. As digital technologies continue to gain in momentum and importance, it has become clear that digitization has features that do not fit well into traditional economic models. This suggests a need for a better understanding of the impact of digital technology on economic activity, and Economic Analysis of the Digital Economy brings together leading scholars to explore this emerging area of research.