Information is an undeniable force resulting implicitly from research. Inconsistent studies do not deserve to be even started. Statistical analysis plays a substantial role in gathering information, using descriptive methods or analytical ones. Confidence level for different measures (the mean is the most handle) and also statistical test are used to compare populations, exploiting samples. In this paper some aspects concerning sample size, statistical significance and the difference observed are described. Mathematical formulas are presented to account for the relations between sample size and statistical significance.