What is a Test Statistic exactly?

The TEST is the type of ysis you need to do, depending on what you want to measure. The TEST STATISTIC refers to the numeric results of the statistical ysis that you conducted on your data. Finally the STATISTIC VALUE refers to the probability that the differences in the results you obtained (comparing the independent variables with your control group) would be likely to have occurred by chance alone, allowing you to reject the null hypothesis or not.