unequal rich countries The<unk>  has been studied around the world, providing estimates on how common<unk>  disorders are. Different criteria or thresholds of severity have sometimes been used. National and international figures are typically estimated by large-scale surveys of self-reported symptoms up to the time of assessment; sometimes a figure is calculated for the occurrence of disorder in the week, month or year prior to assessment–a point or period<unk> ; sometimes the figure is for a person's lifetime prior to assessment–the so-called lifetime<unk> .
Prevalence of mental disorders
Prevalence of birth control
Prevalence of tobacco use
Prevalence of teenage pregnancy
Sex differences in psychology
Infection rate
Cancer survival rates
Epidemiology of child psychiatric disorders