Empirical Rule

Front

What is the Empirical Rule?

Back

The Empirical Rule states that for a normal distribution, approximately 68% of the data falls within one standard deviation of the mean, about 95% falls within two standard deviations, and about 99.7% falls within three standard deviations.

Front

What percentage of data falls within 1 standard deviation of the mean according to the Empirical Rule?

Back

68%.

Front

What percentage of data falls within 2 standard deviations of the mean according to the Empirical Rule?

Back

95%.

Front

What percentage of data falls within 3 standard deviations of the mean according to the Empirical Rule?

Back

99.7%.

Front

What percentage of people are more than 2 standard deviations above the mean?

Back

2.5%.

Front

What percentage of people are more than 3 standard deviations above the mean?

Back

.15%.

Front

What does it mean for data to be 'one standard deviation above the mean'?

Back

It means the data point is greater than the mean by an amount equal to one standard deviation.

Front

In a normal distribution, what does the area under the curve represent?

Back

The area under the curve represents the total probability of all outcomes, which equals 1 (or 100%).

Front

What is a standard deviation?

Back

A standard deviation is a measure of the amount of variation or dispersion in a set of values.

Front

How do you calculate the standard deviation?

Back

To calculate the standard deviation, find the mean of the data set, subtract the mean from each data point, square the result, find the average of those squared differences, and then take the square root.