Interkuartil

Interkuartil, also known as the interquartile range (IQR), is a statistical measure used to describe the spread or dispersion of a dataset. It specifically quantifies the range within which the middle 50% of the data values lie. The interquartil is calculated as the difference between the third quartile (Q3) and the first quartile (Q1), expressed mathematically as IQR = Q3 - Q1.

The quartiles divide a sorted dataset into four equal parts. The first quartile (Q1) marks the 25th percentile, where 25% of the data falls below this value. The third quartile (Q3) marks the 75th percentile, with 75% of the data below it. The interkuartil therefore captures the central dispersion, reducing the influence of outliers compared to measures like the range.

The interquartile range is widely used in descriptive statistics and data analysis to assess variability and detect outliers. Values that fall below Q1 - 1.5 * IQR or above Q3 + 1.5 * IQR are often considered outliers. Since the IQR is based on quartiles, it is a robust measure resistant to the effects of extreme values.

In practical applications, the interquartile range helps in understanding the spread of data in fields such as finance, quality control, and social sciences. It provides insight into the consistency or variability within a dataset, complementing other measures like the mean and standard deviation for comprehensive data analysis.