Is it possible to have a negative z score

A standard normal distribution SND. It is useful to standardized the values raw scores of a normal distribution by converting them into z-scores because:. As the formula shows, the z-score is simply the raw score minus the population mean, divided by the population standard deviation. The value of the z-score tells you how many standard deviations you are away from the mean. If a z-score is equal to 0, it is on the mean. A positive z-score indicates the raw score is higher than the mean average.

A negative z-score reveals the raw score is below the mean average. For example, if a z-score is equal to -2, it is 2 standard deviations below the mean.

Another way to interpret z-scores is by creating a standard normal distribution also known as the z-score distribution or probability distribution. Figure 3. A standard normal distribution SND and normal distribution.

You can see the 0. So each z-score will be printed right next to each raw score. Some z-scores will be positive whereas others will be negative. This means that it is above the group mean. See all of the positive z-scores in our example? For example, look at the top most z-score, 0.

MarianD 1, 2 2 gold badges 7 7 silver badges 16 16 bronze badges. Simply put, a z-score is the number of standard deviations from the mean a data point is. Add a comment. Active Oldest Votes. So for a z-score of -2, with a p-value of 0. Improve this answer. A z value of —2 yields a probability of 0.

Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Z-scores can take on any value between negative infinity and positive infinity, but most z-scores fall within 2 standard deviations of the mean. The higher the absolute value of a z-score, the further away a raw value is from the mean of the dataset. The lower the absolute value of a z-score, the closer a raw value is to the mean of the dataset. Your email address will not be published. Skip to content Menu.