Definition of Histogram:

« Back to Glossary IndexWhen you think of the word “histogram,” you might think of an old-school history book with a list of events or statistics on each page. But in Lean Six Sigma, a histogram is a graph that shows how often data occurs in different ranges. It’s a tool that can be used to help you identify where your process has problems and how to make adjustments.

In Lean Six Sigma, a histogram is used as part of the Define phase of the DMAIC (Define–Measure–Analyze–Improve–Control) process. The purpose of this tool is to help you understand your data by breaking it down into smaller groups, or bins, and then counting how many data points fall within each bin.

## Overview: what is a histogram?

A histogram is a graphical representation of the frequency distribution of a set of data. It can be used to determine whether the data are normally distributed and identify outliers.

A histogram is created by dividing the range of observed values into intervals and counting how many values fall into each interval. The resulting diagram shows how much variation there is in the data.

The histogram can help you assess whether your process is stable or not, which is important when working with processes that produce defects. If you have more than one defect, you need to look at why this happened before making a change to your process.

In Lean Six Sigma, histograms are used to help identify problems with processes, as well as potential improvements that could be made.

## 3 Benefits of histograms

The histogram tool in Lean Six Sigma is one of the most important tools to help you create a more efficient, quality-focused organization. It can be used to analyze and improve your processes, as well as help you spot opportunities for process improvement.

Some of the benefits include:

### 1. Easy to use

Histograms are simple to use, and they require no special training or knowledge on the part of any user who wants to use them. They’re also easy for non-technical users—such as business analysts or project managers—to understand, which makes them ideal for identifying and improving processes that have been difficult for other teams to grasp before now.

### 2. Effective at spotting problems

Histograms are particularly effective at spotting problems in your process because they show you exactly where those problems lie so that you can find solutions quickly and easily without having to do a lot of digging around first. This saves time and money by allowing everyone involved with improving production processes access directly into what’s happening inside their own companies instead of relying on outside sources.

### 3. Provide context for other data analyses

Histograms provide context for other data analyses in Lean Six Sigma projects such as Pareto analysis or control charting. In other words, you can use a histogram to see whether or not your data looks like it might follow a normal distribution, which can help you decide if you need to use something else like Pareto analysis or control charts instead of just relying on the basic averages from your sample set of data points.

## Why are histograms important to understand?

Histograms are important to understand because they provide a visual representation of data. They can be used to analyze the distribution of a variable, which is a useful tool for understanding the data’s shape and how it compares to other variables. You can use them to compare different types of data, or you can even use them to compare two different measurements of the same variable.

The histogram tool in Lean Six Sigma helps you visualize your data in a way that makes sense out of raw numbers. It shows you how often each value occurs in your data set and allows you to determine whether there are any outliers or other unusual occurrences.

## An industry example of using a histogram

Histograms are most commonly used by practitioners of Lean Six Sigma to help analyze data from their processes, or “continuous improvement,” and determine whether there is an underlying pattern that affects the outcome of their process.

Histograms can be used to identify patterns that are not immediately visible in numerical values. For example, if a company is looking at its monthly sales figures and they notice that one month has significantly higher sales than normal, they might assume there was an error with their system or that it was simply an anomaly. However, if they were able to look at the distribution of those sales numbers over time (i.e., through a histogram), they might discover that it was actually part of a trend—perhaps the company offered some sort of promotion during one month which drove up their sales dramatically.

Histograms are also useful because they allow you to visually compare two processes side-by-side without having to do any math or statistics on your own—just look at where each process’s histogram fits in relation to one another!

## 3 Best practices when thinking about histograms

Histograms are a great tool for evaluating data and making decisions. They can be used to show the distribution of a single variable, or to compare several variables.

There are a few best practices that you should keep in mind when using this tool:

### 1. Keep your data simple.

It’s best to use only one variable when creating your histogram. If you want to compare two variables, it’s better to create two separate histograms rather than trying to show both on the same graph.

### 2. Don’t include too many categories in your histogram.

It will become hard to read if there are too many bars or bins on a single graph. The rule of thumb is that there should be no more than five bins on each axis (horizontal and vertical).

### 3. Label each bar.

You should always label each bar with some kind of key or legend so that people can see what each one represents without having to hover over them or read text—this is especially important if you’re showing several different variables at once.

## Frequently asked questions (FAQs) about histograms

**Q: What is a histogram and why is it used?**

A: A histogram is a graphical representation of data. In the context of Lean Six Sigma, a histogram helps you understand how well your process is performing by showing you whether there are any outliers in your data set. If there are any outliers, it means that something unexpected happened during production—maybe someone forgot to turn off an oven or something else unusual happened that caused that particular data point to deviate from the rest of the data set.

**Q: Is a histogram the same thing as a bar graph?**

A: It is similar to a bar graph, but instead of using bars, it represents the data with rectangles (bins) and then counts how many observations fall into each bin. The bins are usually defined by range boundaries and are set up so that they all have approximately the same width.

**Q: How do you create a histogram?**

A: A histogram can be created in two ways: manually or by using the histogram feature in Minitab’s Design-of-Experiments (DOE) module.

To create a histogram manually, you need to enter your data into columns on an Excel spreadsheet and then use the ‘column chart’ option to display it as a histogram.

If you are using Minitab’s DOE module, you can automatically generate histograms from your experiment results by clicking the “Create” button at the top left corner of the DOE Results table window, which will open up the Create Experiment Results dialog box. In this dialog box, click on “histograms” and then choose either “Individual” or “Scatterplot.”

## The best tool for quick visuals

The histogram is going to help you, the Lean Six Sigma practitioner, greatly because it has a better quick visual representation of process data than any other tool. The histogram will also provide you with a quick visual representation of your process data compared to your specification limits. That is really important in trying to understand how well your process is performing. In other words, when you move towards a more continuous improvement type process and improvement mindset, the histogram is an excellent tool for doing that.