A histogram is a commonly used graphical representation method. It is widely used to represent continuous-discrete data on an interval scale. It is used to measure numerical data present on large scale. This article briefly covers everything about histogram; its definition, parts, importance and uses, how to plot histogram and comparisons between histogram and bar graphs.

Definition of Histogram

A histogram comprises rectangles with different base sizes and distances between class boundaries. Each rectangular bar represents a different sort of data linked to the others. The heights of rectangles are proportional to the frequency of stimulation.

• The horizontal axis depicts the numerical range
• The vertical axis represents the amount of data in each range (frequency)

Based on the data used, the range of numbers is determined.

Parts of a Histogram

The following are the parts of a histogram:

1. The title describes the information contained in the histogram.
2. The range of measurement values is represented on the X-axis in continuous intervals.
3. The number of occurrences of the value is represented on the Y-Axis with respect to the intervals given on the X-axis.
4. The height of the bar and its width represents the number of occurrences of the values and the range covered. The width of all bars in a histogram with equal bins should be the same.

Importance of a Histogram

A histogram can help you visually observe how the data is spread. Histograms can display a large amount of data and the frequency with which data values appear. The median and distribution of data can be determined using a histogram. It can also point out any irregularities or gaps in the data.

Uses of Histogram 

A histogram should be used when:

• The information is numerical
• Determining if the output of a process is distributed approximately regularly. You want to see the form of the data distribution
• Determine whether a technique can meet the needs of the customer
• Examining how the result of a supplier’s business appears
• Examining whether a process has changed from one time period to the next. Determining whether the outcomes of two or more procedures vary

How to Plot a Histogram

Here is how to plot a histogram step by step:

• First of all, one needs to determine the same scales for the X and Y axis
• Then, mark class intervals and frequencies on the X and Y-axis respectively
• Draw rectangles of bases equivalent to class intervals and of heights equivalent to related frequencies
• In case intervals are not equal, the area of each rectangle is in proportion to the class frequency. If the intervals are equal, each rectangle’s height is in proportion to the class frequency

A Comparison Between a Bar Chart and a Histogram

Bar chart and histogram are commonly used graphical representation tool. They seem similar to each other but are slightly different. The difference can be easily observed in the bars. In a histogram, the bars are adjacent to each other. However, they aren’t adjacent or continuous in bar graphs. Below are some more points of differentiation.

• A bar graph is a widely used graphical representation of categorical data in which rectangular bars of varying lengths are drawn in proportion to the respective value
• A histogram is a common tool of graphical representation used for numerical data that differentiates the data into continuous ranges of numbers, generally represented like a vertical bar

Conclusion

A histogram is used to display the frequencies of different types of data. It is a graphical representation of data in which the data is organised into continuous number ranges, with each range represented by a vertical bar. It is one of the most commonly used graphical representation tools. It is used to represent large sets of data. It helps in comparative analysis of change in data in different periods, and determines the change in output when the number of processes is increased to estimate what amount of product meets the demands and for many more purposes. A histogram has an X and Y-axis. One represents the range of measurement values and the other the number of occurrences of the value.