Mathematics
Z-Scores (Standard Scores)
Quick fact
In a normal distribution, approximately 68% of all data points have a z-score between -1 and 1, 95% between -2 and 2, and 99.7% between -3 and 3.
Why this is interesting
Imagine you scored 85 on a math test and 70 on a physics test. Which subject did you perform better in? Without knowing the difficulty of each test, how can you fairly compare?