Test Statistic

A test statistic is the computed quantity that summarizes how unusual the observed data appears in a hypothesis testing framework. For example, the difference between two group means may be scaled by a standard error to produce a test statistic. This value is then compared with a theoretical distribution in order to assess whether the result is likely due to chance. In short, the test statistic acts as the bridge that converts raw data into interpretable statistical evidence. It is a key concept for understanding how hypothesis tests work.