Residuals

They represent all the deviations for each data point. In statistical tests that analyze a continuous (a.k.a. variable or numerical) value, they are often used as a supplement to validate the original statistical test. The Analysis of Variance (ANOVA) is an example of test where residuals are used.
Related StatStuff Video: 
   -Section 6-Analyze Phase, Lesson #18 - Hypothesis Testing: Central Tendency – Normal (Compare 2+ Factors)