What is z-score?

What is z-score?

What is z-score? The z-score, also referred to as standard score, z-value, and normal score, among other things, is a dimensionless quantity that is used to indicate the signed, fractional, number of standard deviations by which an event is above the mean value being measured.

How do you map a z score across a Z table?

To map a Z score across a Z Table, it goes without saying that the first thing you need is the Z Score itself. In the above example, we derive that Eric’s Z-score is 0.56. Once you have the Z Score, the next step is choosing between the two tables.

What are positive scores in the Z-table?

Positive scores in the Z-table correspond to the values which are greater than the mean. Here is an example of how a z-score applies to a real life situation and how it can be calculated using a z-table. Imagine a group of 200 applicants who took a math test. George was among the test takers and he got 700 points (X) out of 1000.

What if a Z-Score calculation yields a negative standardized score?

If a z-score calculation yields a negative standardized score refer to the 1st table, when positive used the 2nd table. For George’s example we need to use the 2nd table as his test result corresponds to a positive z-score of 0.67.