# What does a high and a low z-score mean?

Jan 17, 2017

A high $z$-score means a very low probability of data above this $z$-score and a low $z$-score means a very low probability of data below this $z$-score..

#### Explanation:

A high $z$-score means a very low probability of data above this $z$-score. For example, the figure below shows the probability of $z$-score above $2.6$.

Probability for this is 0.47%, which is less than half-percent. Note that if $z$-score rises further, area under the curve fall and probability reduces further.

A low $z$-score means a very low probability of data below this $z$-score. The figure below shows the probability of $z$-score below $- 2.5$.

Probability for this is 0.62% and note that if $z$-score falls further, area under the curve falls and probability reduces further.