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The Top Basic Tools of Quality Tutorial | The Ultimate Guide

Last updated on 24th Aug 2022, Blog, Tutorials

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Shashi Gopal (Quality Manager )

Shashi Gopal is a quality manager and publishes in-depth research on a wide range of subjects. She also has experience in CCNA, ICCNP, Ethical Hacking, Hardware & Networking, Cyber Security, CompTIA, and ELECTRONI.

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What is the histogram?

The visualisation of the distribution of data points in a dataset can be accomplished with the use of an easy-to-use tool and The graph that is utilised most frequently to display frequency distributions called a histogram. The appearance is strikingly similar to that of a bar chart; yet, there are significant distinctions between the two. One of the seven fundamental quality tools, this helpful data collecting and analysis tool is considered to be one of the most important tools. It is able to swiftly uncover patterns and trends, as well as identify outliers.

The following guide will walk you through the three steps necessary to produce an effective histogram:


Step1: Minimum Data Points

It is generally advised that you have at least 50 data points at your disposal before attempting an accurate analysis of a data set. It is impossible to draw logical inferences from your data if you do not have access to a sufficient volume of the data.Simply put, there is a chance that you will not see the pattern in the variation.On the opposite side of this need, one of the benefits of the Histogram is that it allows you to quickly evaluate enormous data sets, so don’t be afraid to collect or analyse A LOT of data. This is one of the advantages of using the Histogram.

Step2: Count the Number of Containers

It is time to compute the number of Bars, which may also be referred to as Ranges or Bins, for your data collection now that you have collected an acceptable amount of data. Your histogram will have a certain number of bars, which will be determined by the total amount of data points that you have collected.It is essential to choose the appropriate number of Bins because doing so might have a significant impact on the visual representation of your data, which in turn could cause you to draw the incorrect conclusion.You can choose the appropriate number of Bars by consulting the table that can be found below, which was taken from The Quality Toolbox. In addition, I feel it necessary to mention that in certain instances, the number of Bins was simply determined by taking the square root of the overall data size. Histogram Displaying Student Performance.

histogram grap

Step3: Determine Bin Width

After you have established the total number of Bins that will comprise your Histogram, the next step is to compute the Width or Range that will apply to each individual Bin.In order to accomplish this, take the complete data range, subtract the minimum data point from the maximum data point, and then divide the result by the total number of bins.If the highest possible score on the test was 100, and the lowest possible score was 20, and you were producing a histogram of students’ test scores, then the range of your data would be 80. (100 – 20).After that, you are able to divide your data Range, which is 80, by the entire number of Bins, which for this example will be 8. Therefore, the width of each Bin is equal to 10, or 80 divided by 8.If you don’t keep the widths of all of the bins the same, the distribution of the data will be off because of this, which is why it’s crucial to choose the correct number of total Bins.

Usage of histogram:

  • The use of a histogram as a preventative method in “Plan Quality Management” is one way to make improvements to processes.
  • We determine the groups of reasons that affect the most by looking at historical data.
  • We choose processes to enhance based on the categories they have an impact on the most.
  • For instance, when the frequency of IES, MCC, and EDR events increases, we may choose to implement changes to the “Collect Requirement” and “Define Scope” procedures.
  • We are able to detect causes of poor performance with the use of “Control Quality,” which assists in enhancing processes and the work products they produce.
  • Histogram is a great tool for taking corrective steps because of the way it analyses the factors that contribute to poor performance.

Compare the Pareto Chart with a histogram:

    HistogramPareto Chart
    1.A histogram is a type of bar chart that displays the distribution of variables or the factors that contribute to issues. 1.A particular kind of histogram known as a Pareto chart is used to illustrate the factors that contribute to issues in the order of their influence. It is a helpful tool for prioritising corrective action by displaying errors in descending order of frequency, with the errors that have the largest impact presented first.
    2.The cause of a problem is represented as a column in a histogram, and the height of the column indicates the frequency with which that source of trouble occurs. 2.In the Pareto analysis, there is also an arc included that represents the cumulative percentage of the frequency of the causes.
    3.A histogram is a type of bar chart in which the height of each bar represents the frequency of the event being analysed. 3.A special kind of histogram known as a Pareto chart displays information according to the 80/20 rule. In this section, the visual presentation of the most relevant 20% of the causes is done in descending order of frequency.

HISTOGRAMS As a Quality Instrumental Tool:

  • Variation can be found in every environment, as is common knowledge. It is unavoidable in the final product of any process, whether it be one that produces goods, provides services, or is administrative in nature.
  • We are also aware that it is impossible to maintain a steady state for all of the factors all of the time. This is one of the most significant problems that a team working on quality improvement faces. To be more exact, in order to lessen unpredictability.
  • A histogram is a graphical representation that summarises the variance that can be found in a set of data. Because it is graphical in nature, the histogram makes it possible for us to recognise patterns that would otherwise be difficult to recognise in a straightforward table of numbers.
  • Histograms provide members of quality improvement teams with a kind of x-ray vision that enables them to diagnose faults.
  • On a more global scale, a histogram is distinguished by three important qualities, which are as follows:
      1. 1.The middle of the
      2. 2.The width of the
      3. 3.The contours.
  • Additionally, quality improvement teams can use these three criteria to locate the COPQ resident in a process.

Compare the bar chart with a histogram:

  • As I mentioned earlier, the Histogram is a sort of bar chart due to the fact that both of these types of charts present data using vertical bins.
  • However, there is a clear distinction between a bar chart and a histogram, and you need to be able to determine which of the two to employ in order to successfully complete the data analysis that you are doing.
  • Your data will be grouped into Bins or Ranges by a Histogram, whereas a bar chart would present discrete data according to categories.
  • Instead of a histogram, you should make use of a bar chart if your data can be broken down into specific groups or categories. Developing a Histogram for the Data
  • If you already have some data and you want to generate a histogram so that you can analyse the pattern of variation, that’s fantastic!

What are some Applications of a Histogram:

It is possible to identify patterns and trends in data with the use of histograms. In addition to this, they shed light on the composition of the data. In general, they are useful instruments for the following:

  • Determining a data set’s dominant pattern or primary tendency.
  • Recognizing anomalous data.
  • Figuring out whether the data follow a normal distribution or if they are skewed.
  • Discovering odd occurrences in the world.
  • Conducting an analysis of the spread of a group of data points.
  • Finding unusual occurrences.
  • Visualizing huge datasets.

What Are the Top Attributes That Make a Histogram Useful?

A histogram is a useful tool for data visualisation since it possesses the seven properties listed below:

1. Simple in both comprehension and application: A histogram is something that can be understood in a matter of moments. Reading and understanding it is not difficult at all.

2. In a Short Time Imagined: You can quickly construct a histogram due to the fact that creating one is not difficult. Because of this, recognising patterns and outliers is a breeze.

3. Helps You Detect Trends: When looking at a histogram, it is common practise to inquire about the positions of the highest and lowest points. This enables you to identify patterns.

4. Helps You Identify Anomalies: When anything brand new takes place, there will be an abnormality. If you examine a histogram, you can find that one of the bars has a peak or a trough in the data. This reveals that there was an event that occurred inside the given data range.

bar chart vs histogram

Why Do You Need to Make Use of a Resource Histogram?

  • The usage of a resource histogram is one method that project managers employ to ensure that their resources are being utilised effectively.
  • They provide a fast and uncomplicated method for analysing the use of available resources. The American Society for Quality (ASQ) cites the histogram as the quality tool that is utilised the vast majority of the time.
  • The resources that are recorded in the resource histogram are unique to a certain time period, regardless of whether that time period is currently occurring or will occur later on in the project.
  • The project manager can use this information to better plan the distribution of the resources throughout the life cycle of the project.
  • The resource histogram, which is comparable to a Gantt chart, details the amount of each resource that was utilised throughout each time period (which is also a stacked bar chart).
  • Nevertheless, a Gantt chart is a more sophisticated tool for project management that can also be used to schedule, assign, and track activities, resources, and other elements of the project.
  • The Gantt chart is one of the most important tools for project managers to employ when it comes to resource planning and scheduling projects.
  • Almost all project management software includes this chart. Cloud-based ProjectManager is a software application that goes beyond the capabilities of classic project management tools such as Gantt charts.
  • It keeps tabs on both human and nonhuman resources, and it has the ability to establish a baseline for comparing actual effort to what was anticipated.

What Exactly Is an Example of a Resource Histogram?

  • In the context of project management, a resource histogram is a stacked bar chart that is utilised for the purpose of resource allocation.
  • It’s essentially a resource planning graph that shows, over the course of a certain amount of time, how much time is scheduled to be spent working with each resource. Additionally, it can be utilised to ascertain the availability of resources.
  • Having access to the resources you require at the exact moment you require them is essential to the successful completion of the project’s duties.
  • Histograms of the resources available are used by project managers as they monitor the project and track its progress.
  • They are able to get a general picture of where their resources are located and how they are being utilised thanks to the information that is gleaned from a resource histogram.
  • Histograms of resources contain two axes: one horizontal and one vertical. The horizontal axis displays the range or value of gaps between variables, while the vertical axis depicts the number of times that interval happened.
  • The bars are a representation of the available resource. In addition, there is a legend that describes each individual bar.


Histograms are not the same as bar charts; the primary distinction between the two lies in the fact that a histogram displays data that is continuous, contiguous, and organised into equal intervals. In a graph, there is no space with between the two bars, however in bar charts, there is space in between the bars.In terms of quality, the histogram is utilised to determine the reason behind an issue that has arisen within the system and to provide an efficient graphical representation in numerical format to the stakeholders. The team in charge of project management as well as any other team that is not directly involved in the project should have no trouble understanding the information depicted in such a graphic depiction.Because the graph displays the real numerical data, the histogram is utilised to indicate that there has been an improvement in the product’s quality.

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