Ask anyone who has attended Stats101 and s/he will tell you that they understand Z-score. But, really? Could you answer the following questions without thinking?

  1. What is the mean of z-scores?
  2. What is the standard deviation of z-scores?
  3. What is the sum of squared z-scores?
  4. Is the z-score distribution the same as the original distribution of sample values?
  5. What do z-scores above 0 mean?

If you cannot answer them without thinking, then you don’t really understand …