What is the formula used to calculate the lower quartile?

The formula for calculating the lower quartile, also known as the first quartile (Q1), is represented by (n + 1)/4. This formula is used to determine the position of the data point that corresponds to the lower quartile in a sorted dataset.

To find the lower quartile, you first need to understand that it represents the value below which 25% of the data falls. By using the formula (n + 1)/4, you effectively find the index of the first quartile in a dataset containing n observations. If the resulting index is a whole number, the lower quartile is the value at that index; if it’s not a whole number, you would interpolate between the closest values in the dataset.

This process ensures that the lower quartile reflects the distribution of the data accurately by precisely locating the point below which one quarter of the sorted values lie. Hence, using this formula is crucial for accurately determining the lower quartile in data analysis and statistical computations.