The DIRAC framework: Geometric structure underlies roles of diversity and accuracy in combining classifiers.

Combining classification systems potentially improves predictive accuracy, but outcomes have proven impossible to predict. Similar to improving binary classification with fusion, fusing ranking systems most commonly increases Pearson or Spearman correlations with a target when the input classifiers are "sufficiently good" (generalized as "accuracy") and "sufficiently different" (generalized as "diversity"), but the individual and joint quantitative influence of these factors on the final outcome remains unknown. We resolve these issues. Building on our previous empirical work establishing the DIRAC (DIversity of Ranks and ACcuracy) framework, which accurately predicts the outcome of fusing binary classifiers, we demonstrate that the DIRAC framework similarly explains the outcome of fusing ranking systems. Specifically, precise geometric representation of diversity and accuracy as angle-based distances within rank-based combinatorial structures (permutahedra) fully captures their synergistic roles in rank approximation, uncouples them from the specific metrics of a given problem, and represents them as generally as possible.

Health human resources in Canada

The article scrutinizes the different health professions in the socioeconomic setting of Canada. This country has a surplus of physicians and, at the same time, shortages in some specialties. In the discussion of the imbalance in the numbers and distribution of this manpower, it is indicated that certain factors affect all occupational groups including: the development of a data system on the health field, the effects of new technologies, and the size of education institutions. In the past, many physicians and other health professionals, attracted by the labor market, have come to practice in Canada. In addition, the supply of home-grown professionals has greatly increased. Based on a national study, four proposals are made to reduce the current and future surpluses: restrict the immigration of physicians, develop regional graduate training programs, reduce medical school enrollments, and address the joint problems of distributing and reducing the supply of health manpower (Au)