A common mistake in using Unique User numbers is adding up Unique User numbers across dimensions. A Unique User metric is only valid for its given set of dimensions e.g. time, browsers. For example, a website may have 100 unique users on each day (day being the dimension) of a particular week. With only this data, one cannot extrapolate the number of weekly Unique Users (only that the Unique User count for the week is between 100 and 700). However, website administrators who can track unique user traffic over a longer period of time can build up a reliable view on their performance against direct competitors within the sector. Online businesses tend to have a static conversation rate ratio between unique users and new business clients.