# Normal scores

## Normal scores :

Normal scores, also known as standard scores or z-scores, are a way of measuring how far a particular score falls from the mean of a dataset. They are calculated by subtracting the mean from the score and dividing the result by the standard deviation. This allows for scores to be compared and understood within the context of the entire dataset, rather than just as a standalone value.
For example, let’s say that a group of students took a math test and the mean score was 80 out of 100 points. John scored a 95 on the test, while Jane scored a 65. In order to understand how these scores compare to the rest of the class, we can calculate their normal scores.
First, we subtract the mean from each score to get the deviation from the mean:
John’s deviation: 95 – 80 = 15
Jane’s deviation: 65 – 80 = -15
Next, we divide each deviation by the standard deviation of the scores:
John’s normal score: 15 / 10 (standard deviation) = 1.5
Jane’s normal score: -15 / 10 (standard deviation) = -1.5
Now we can see that John’s score was 1.5 standard deviations above the mean, while Jane’s score was 1.5 standard deviations below the mean. This gives us a better understanding of how their scores compare to the rest of the class, rather than just looking at the raw scores of 95 and 65.
Another example of using normal scores is in the field of psychology, where they are often used to assess an individual’s performance on a test or assessment. For example, let’s say that a group of people took an intelligence test and the mean score was 100 points. Bob scored a 120 on the test, while Sarah scored an 80. By calculating their normal scores, we can see how their scores compare to the average score of the group.
First, we subtract the mean from each score to get the deviation from the mean:
Bob’s deviation: 120 – 100 = 20
Sarah’s deviation: 80 – 100 = -20
Next, we divide each deviation by the standard deviation of the scores:
Bob’s normal score: 20 / 15 (standard deviation) = 1.33
Sarah’s normal score: -20 / 15 (standard deviation) = -1.33
This shows us that Bob’s score was 1.33 standard deviations above the mean, while Sarah’s score was 1.33 standard deviations below the mean. This allows us to compare their scores to the average score of the group and understand how they performed in relation to the average.
Normal scores are useful because they allow us to compare scores within the context of a larger dataset, rather than just looking at raw scores. They are often used in fields such as psychology and education to assess performance and understand how an individual’s score compares to the average. They are also useful for statistical analysis, as they allow for data to be standardized and compared across different groups or datasets.