A negative z-score indicates that the raw score is lower than the mean average. For example, if the z score is equal to -3, it means that it is three standard deviations below the mean.
can there be a negative z score?
There can be a negative z score. The negative score will depict it is below the mean. Notably, any score with a value less than the population means will have a negative z-score.
how to find z score of a negative number (with examples)
we can find the z score of a negative number from the negative z score table.
Examples of z score of a negative number.
The z score of negative 1(-1)
A z score of -1 means that the data point is exactly one standard deviation below the mean. Z score of negative 1 (-1) will be;
Thus, the value will be 0.15866, which is equivalent to 15.87% of the data points.
z score of negative 2(-2)
A z score of -2 means that the data point is exactly two standard deviations below the mean. Z score of negative 2 (-2) will be;
Thus, the value will be 0.02275, which is equivalent to 2.275% of the data points.
How to read the negative z score table list
To read the negative z score table list, we look up the z value from the row edge then the second-place value is checked on the column on the top. (Click here) for a guide on reading and using the negative z score value on the table list.
what to do when z score tends negative
When the z score tends to be negative, it is below the mean in the denoted standard deviations. Notably, to get the value of the z score, you can read directly from the negative z score or use the positive z score table and subtract the area from the table from 1. For instance, if we calculate the value of the z score and get -3.37,
Calculating the probability of a negative z score
We can calculate the probability of a negative z score by checking the z score values and area from the z score table.
Option 1: from the negative z score table, we have;
Thus, the value of the -3.37 z score is 0.00038
The probability is 0.00038 or 0.038%
Option 2: from the positive z score table and subtracting it from 1, we have;
First, we check the value of 3.37 from the positive z score table
The value of 3.37 is 0.99962
Subtracting the value from 1, we have;
=1-0.99962
=0.00038
Thus, the value of the -3.37 z score is 0.00038
The probability is 0.00038 or 0.038%
How to interpret negative z score
The z score tells us how many standard deviations one is away from the mean. Suppose the raw score is below the mean average when the z-score is negative. A z-score of -3, for example, indicates that the data is three standard deviations below the mean.
what does a negative z score mean
A negative z-score depicts that the raw score (x) is below the mean of the data point. For example, if the raw score is 30, the standard deviation is 10, and the mean of the data is 50. The z score will be;
The -2 z score means that the score is two standard deviations below the mean.