Range (statistics)

Range (statistics)

The range in statistics is a measure of dispersion, a value that represents the spread of a data set. It is the difference between the highest and lowest values in the data set. The range can give a general idea about the spread of the data, but it does not provide information about the data's distribution.

Calculation

The range is calculated by subtracting the smallest value in the data set from the largest value. The formula for calculating the range is:

Range = Maximum value - Minimum value

For example, if a data set includes the numbers 1, 2, 3, 4, and 5, the range would be 5 - 1 = 4.

Limitations

While the range is a simple measure of dispersion, it has several limitations. It only considers the extreme values in the data set and does not take into account the other values. Therefore, it can be greatly affected by outliers. In addition, the range does not provide any information about the data's central tendency or its distribution.

Applications in Medicine

In medicine, the range is often used in medical statistics to describe the spread of data such as patients' ages, blood pressure readings, or the results of a medical test. For example, the normal range for human body temperature is typically stated as 36.5–37.5 °C.

File:Blood pressure chart.png

A chart showing the range of normal, prehypertension, and hypertension blood pressure readings.

See Also

• Mean
• Median
• Mode
• Standard deviation
• Variance