Test statistic

A test statistic is the point estimate of the parameter of interest, obtained from a sample. It is also called the sample statistic.

For instance, if the analyst is interested in the mean of a certain population the sample statistic is the sample mean, which is referred as the test statistic. In order to perform a test of hypothesis this test statistic is standardized. Therefore, the standardized test statistic for the mean of the population becomes:

Standardized test statistic = (Sample mean - Value from Ho)/ Standard deviation of sample mean