Which aspects of our understanding of the impacts of POPs on polar bear populati

Since polar bears were given immunizations, the studies of POPs and infection could be considered experimental. However, all other research has been correlative. The advantage of manipulative experiments is that variables can be controlled, and relationships between effects and their potential causes can be measured directly. These experiments have a greater impact on both the wild population and any captive individuals used, and therefore are more difficult, both ethically and logistically, than correlative studies. While correlative studies are easier to conduct, their main weakness is that correlations may not clearly identify causative effects.