# Question to clarify my understanding; regards to z-scores.

• October 17th 2007, 07:16 AM
beetz
Question to clarify my understanding; regards to z-scores.
why is it ok for a z-score to be -2 when all probabilities lie on the interval [0,1]?

i'm reviewing for a test, and not exactly sure.
thanks!
• October 17th 2007, 07:27 AM
topsquark
Quote:

Originally Posted by beetz
why is it ok for a z-score to be -2 when all probabilities lie on the interval [0,1]?

i'm reviewing for a test, and not exactly sure.
thanks!

Because the probability is a function of z, and has a (effective) domain of $( -\infty, \infty)$ for a normal distribution. The probability lies in the range [0, 1], not z.

-Dan