AI engineering glossary · Probability
What is z-score?
Z-score (also called Standard score): The number of standard deviations a value lies above or below the mean: z = (x - mean) / standard deviation. It puts values from different scales on a common footing and flags unusually large or small values.
Z-score: an example
A student scoring 82 when the class mean is 70 and standard deviation is 6 has z = (82 - 70) / 6 = 2.
Related terms
- Normal distribution
- Standard deviation
- Standardisation
More Probability terms
- Addition rule
- At-least-one probability
- Base rate
- Base rate fallacy
- Bayes' theorem
- Bayesian probability
- Bernoulli distribution
- Binomial distribution
Where you learn it
Z-score is part of the AI Engineering Program, which teaches it with notes, a hands-on lab and an exam. The first lesson is free.