Histograms

Back to Statistics Summary In the above histogram, the bins represent groups of 300

A Histogram is a graphical representation or summary of the frequency of certain groups of data where the frequency is located on the y-axis and the data groups (known as classes or "bins") are located on the x-axis. These classes or "bins" are groupings of data that cover a range of x-coordinates, such as 0-9, 10-19, 20-19, etc.

Histograms visually depict: - The median or center of the data - The range or spread of the data - Any skewness in the data -- if the histogram has any slants etc. - The presence of outliers - The presence of multiple modes (or peaks) of the data A Histogram can be converted into a probability distribution by dividing the number contained in the bins by the total number of data points. Histograms can convey the following: Shape of the Frequency Distribution Symmetry of Distribution Modality
 * Just as histograms give a summary of the data set, so can box plots and 5-Number Summary.

Histograms are often used in [|photography]to convey the accuracy of the exposure of a photograph. Below is an example of this kind of histogram, the left side representing the dark or black areas of the photo, and the right side representing the light or white areas.

Above is a histogram representing the test scores of a group of students. It is clear that the most frequent grade received by the students fell in the 40-50 range, which represents the mean, median and mode of the set of data. The above histogram has symmetry of distribution.

Practice Problems with Histograms

Histogram Bibliography