In probability and statistics, 1.96 is the approximate value of the 97.5 percentile point of the standard normal distribution. 95% of the area under a normal curve lies within roughly 1.96 standard deviations of the mean, and due to the central limit theorem, this number is therefore used in the construction of approximate 95% confidence intervals. Its ubiquity is due to the arbitrary but common convention of using confidence intervals with 95% coverage rather than other coverages (such as 90% or 99%). This convention seems particularly common in medical statistics, but is also common in other areas of application, such as earth sciences, social sciences and business research.