What does the frequency density tell you in a histogram?

Frequency density in a histogram shows how often data points occur within each interval relative to the interval's width.

In a histogram, the frequency density is used to create bars that represent the distribution of data. Each bar's height is determined by dividing the frequency (the number of data points) by the width of the interval (or bin). This method ensures that the area of each bar is proportional to the frequency of data points within that interval. By using frequency density, histograms can accurately represent data even when the intervals are of different widths.

For example, if you have a histogram with intervals of varying widths, simply plotting the frequency might give a misleading picture. A wider interval might appear to have more data points just because it covers a larger range, not because it actually has a higher frequency. Frequency density corrects this by normalising the frequency according to the interval width, allowing for a fair comparison between intervals.

Understanding frequency density is crucial for interpreting histograms correctly. It helps you to see the true distribution of data, making it easier to identify patterns, trends, and outliers. When you look at a histogram, the height of each bar tells you how dense the data is in that interval, giving you a clearer picture of how the data is spread out across different ranges. This is particularly useful in subjects like statistics and data analysis, where accurate representation of data is essential.