Research examining the effects of childhood exposure to domestic violence is also limited by a range of methodological problems. Despite this, however, sufficient evidence from the body of studies exists to conclude that such exposure has adverse effects. The specific effects may differ depending on a host of variables, such as the children's ages, the nature and severity of the violence, the existence of other risk factors in the children's lives (for example, poverty, parental substance abuse), and whether the children are also directly physically abused. In general, childhood exposure to domestic violence can be associated with increased display of aggressive behavior, increased emotional problems such as depression and/or anxiety, lower levels of social competence, and poorer academic functioning.