London businesses benefit from the city’s ‘diversity bonus’ – so current immigration policies are unhelpful. There should be a greater focus on workers’ welfare

London’s diversity is a cause for celebration for many, but does it have a positive impact on the city’s economy? Max Nathan argues that companies and markets directly benefit from London’s mix of cultures. Unfortunately, current government policy towards migrants and ethnic minorities does very little to maximise the potential of diverse workplaces

Futility Analysis in the Cross-Validation of Machine Learning Models

Many machine learning models have important structural tuning parameters that cannot be directly estimated from the data. The common tactic for setting these parameters is to use resampling methods, such as cross--validation or the bootstrap, to evaluate a candidate set of values and choose the best based on some pre--defined criterion. Unfortunately, this process can be time consuming. However, the model tuning process can be streamlined by adaptively resampling candidate values so that settings that are clearly sub-optimal can be discarded. The notion of futility analysis is introduced in this context. An example is shown that illustrates how adaptive resampling can be used to reduce training time. Simulation studies are used to understand how the potential speed--up is affected by parallel processing techniques.Comment: 22 pages, 5 figure

The psychology of voting action : on the psychological origins of electoral research, 1939-1964

This article examines the development of psychologically oriented voting behavior research between 1939-1964. It intends to show the psychological basis of the Columbia and Michigan approaches and its implications for the analysis of electoral behavior. It is argued that, in spite of the large differences commonly perceived between these two approaches, there is much similarity between them, both with regard to their psychological roots as to their principal conclusions

Conflict of Laws in the Uniform Commercial Code

Pulsatilla vernalis is one of several endangered plant species that benefit from wildfires and small scale disturbance events that repel competing vegetation and create open patches in the vegetation cover. Previous studies argue that Pulsatilla vernalis is decreasing in numbers due to vegetation changes associated with the decrease in wildfires, forest grazing and changes in forest management. In this study, 17 populations of P. vernalis were inventoried in order to examine if soil and/or vegetation structures affect the population structure of P. vernalis (i.e. population size, presence of flowering individuals, density of juveniles) and if performed conservation attempts in the populations have been positive for P. vernalis. This was done by counting the number of vegetative, flowering and juvenile individuals and examining soil and vegetation structure in the populations. The population sizes were then compared with estimates of population sizes from earlier inventories of P. vernalis at the same localities. The study also presents specific recommendations for an improved conservation management of P. vernalis. The results of this study show that mechanical conservation management had a positive effect on the population size and that open areas in the vegetation cover provided better conditions for viable populations of P. vernalis. To prevent the trend of decreasing population sizes of P. vernalis, conservation measures must be carried out to repel competing vegetation and to restore or maintain open patches in existing populations