What percentage of the population is represented within 1 Standard Deviation?

In a normal distribution, which is bell-shaped, approximately 68% of the data falls within one standard deviation of the mean. This is a fundamental concept in statistics known as the empirical rule, or the 68-95-99.7 rule. This rule states that:

• About 68% of the data lies within one standard deviation from the mean.
• About 95% falls within two standard deviations.
• About 99.7% is within three standard deviations.

Understanding the placement of data around the mean is crucial for counselors when evaluating assessments, making decisions based on performance metrics, or understanding student populations. The significance of this percentage is that it reveals how much of the population can be considered typical or average within a given dataset. This knowledge aids in identifying outliers and providing context when analyzing scores or behaviors in educational settings.