A histogram is a data display that shows frequencies of data values in intervals of the same size. The height of the bars shows the frequency of data in the interval it represents.

Depending on the shape of the histogram, we can infer how the data is distributed. The most common distributions are symmetric, skewed right, and skewed left. Let's analyze these one at a time.

Symmetric

In this case, the histogram has a peak at its center. The peak divides the histogram evenly. The data on the right is approximately a mirror image of the data on the left. If we connect the tops of the bars with a curve, it will be bell-shaped.

Additionally, when the bars are roughly the same height, the distribution is still symmetric. However, this special case is most commonly known as a uniform distribution.

Skewed Right

If the histogram has its peak on the left and the tail of the graph extends far to the right, the distribution is skewed right. Most of the data in this type of distribution is on the left.

Skewed Left

Conversely, if the histogram has its peak on the right and the tail of the graph extends far to the left, the distribution is skewed left. This time, most of the data is on the right.

Conclusion

We can characterize the basic shape of a distribution by making a histogram and seeing where the peak and the tail of the graph are located.

Exercise