In a box plot, what does the black line through the box indicate?

In a box plot, the black line that runs through the box represents the median of the data set. The median is the value that divides the dataset into two equal halves, with 50% of the data points lying above and 50% lying below it. This central line effectively indicates the middle point of the data when it is arranged in ascending order, making it a crucial measure of central tendency, especially in skewed distributions.

In contrast to the median, the mean is the average of all data points and is not directly displayed in a box plot. Similarly, the mode, which represents the most frequently occurring value in the dataset, and the range, which indicates the difference between the maximum and minimum values, are also not depicted by the line through the box. Thus, the presence of the line distinctly shows where the median lies within the distribution of the data, emphasizing the box plot's utility in visualizing central tendency along with the variability and spread of the data.