Interquartile range

What Interquartile range is

The interquartile range (IQR) is a measure of spread in statistics. It is the difference between the third quartile (Q3) and the first quartile (Q1).

Steps for calculating Interquartile Range:

  1. Arrange the data in numerical order.

  2. Find the median, which is the middle number.

  3. Calculate the lower quartile (Q1) by taking the median of the lower half of the data.

  4. Calculate the upper quartile (Q3) by taking the median of the upper half of the data.

  5. Subtract the lower quartile (Q1) from the upper quartile (Q3) to get the interquartile range (IQR).

Examples

  1. Interquartile range is often used to identify outliers in a dataset. For example, a retailer may use the interquartile range to identify customers who are spending significantly more than the average customer.

  2. Interquartile range is also used to measure the spread of data. For example, a medical practitioner may use the interquartile range to measure the spread of a patient’s blood pressure readings over a period of time.

  3. Interquartile range can also be used to quickly identify large gaps between data points. For example, a financial analyst may use the interquartile range to quickly identify large discrepancies between stock prices.

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