A histogram is a way to graphically represent information or data and is also known as a bar chart. They are accessible to show things such as frequency of occurrence and categories and are created with two axis, one horizontal and one vertical. They are also easy to make within Excel using the data you have on your spreadsheet.
What are histograms and how are they used
Histograms are generally used to create a visual summary of information. It can be almost any kind of data as the written information is transformed into the chart with vertical blocks – how many blocks depends on the number in the field. So, if you measured how often something happened in a week, each of the vertical columns would represent the number for each day of the week.
Histograms also show statistical information such as the mean value which is the average across the blocks, the maximum value in the highest block and minimum value in the lowest block. The number of blocks indicates the number of items measured such as days of the week, months of the year or other categories.
Monitoring trends is another use for histograms. You could look at a year with twelve sections, one for each month and a vertical line that is split into temperatures. This lets you see how the temperatures change during the year. A similar idea would be household income during the year or time spend at worth across a week.
Benefits of histograms
Histograms are accessible because they let you quickly and easily compare data, see trends or patterns and can work with vast ranges of information; allowing users to optimise decision making. They do work best when using more extensive data ranges such as how many times a college student has returned home during the last twelve months, so colleges could see how much time students spend away from campus.
Examples of histograms
There are hundreds of different examples of histograms and the data they contain but here are a few examples.
The average height of a group of people is one easy histogram. By adding the height data for ten people into a spreadsheet, you can create a histogram showing how many people are each height. This would show you the average height, how many people were a certain height and how many people were over or under a certain height.
The average reading of 30 people for their cholesterol levels with one axis being the cholesterol level and the other the relative frequency. It allows you to see how many people have cholesterol levels over a certain point, what the percentage of people that have a specific reading and how many are under the recommended level.
How to create a histogram
The process of creating a histogram in Excel is a relatively simple one with lots of different variations you can use to personalise the results further.
First, you need to enter the data labelling the column with what kind of data is contained. Let’s say column A is a list of the test score results for a group of 15 students. So A2-A16 would each contain a single number – the test score.
Then click Insert > Insert Statistic Chart > Histogram. Alternatives, you can go to the All Charts in the Recommended Charts tab and select the one you want. Next, you want to look at the design and format options to make the chart look as you want. These can also be found under the Chart Tools section on the ribbon.
If you want to configure the histogram bins, then right-click on the horizontal axis of the charge and click Format Axis > Axis Options. You can choose a number of options including:
- By category – chooses whether text or numerical based
- Automatic – allows Excel to pick what seems right
- Bin width – enables you to set a numerical number for the width of the bin
- Number of bins – will let you choose the number of bins
You can also select style elements such as how the histogram looks, colours and if you want to add labels to the axis. This all lets you get the chart to look the way you want as well as containing the information on the spreadsheet.
