A Guide to Scatter Diagram in PMP

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30th Jun, 2022
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12th Apr, 2022
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A Guide to Scatter Diagram in PMP

If you’re a project manager, you’ll know that making decisions is a part and parcel of your job, daily. These decisions don’t only include the kind of team you should pick for projects or how regularly you should meet. The primary responsibility of every project manager is always focusing on projects' goals and ensuring that they are met. They should do this while also considering resource constraints, so that it doesn’t affect the implementation process. But this is not the tricky part – the tricky part is making sound, informed decisions when there are a thousand variables at play. Most of these variables are interdependent, affecting the outcome in various ways. So, finding if these variables interact and the correlation between them is extremely important, even if it’s in the context of project management. 

This is where project management courses help you through creating a holistic learning experience covering various concepts, approaches, and tools that are handy in project management. But how do you do that? By using tools, of course. And one such tool that does exactly this is a Scatter diagram. Any math or commerce students in your house? Ask them about this, they’re sure to know. However, telling you all you need to know about Scatter Diagrams in PMP and why you need them is my job (even though I hate Math). So, let’s get stated! 

What is a Scatter Diagram?

A scatter diagram is a simple representation that is used to find out the correlation between two variables. These variables ae plotted along the X and Y axis on a two-dimensional graph. The first variable is independent; however, the second variable is dependent on the first one. The pattern, or markings that finally comes up represents the relationship/association between the two. A scatter diagram, also known as a scatter graph, usually looks like a collection of tiny dots that’s wither all over the place, or in a slope of some kind. If there is a relation between the two variables, it’s called a correlationScatter Diagrams in PMP usually tell us how a change in the independent variable causes a change in the value of the dependent one, and by how much. 

The KnowledgeHut pmp prep course online covers all the project management tools and techniques in detail and equips you to choose the right problem-solving tools for every situation. According to the PMBOK Guide, “a Scatter graph is one that shows the relationship between two variables. Scatter diagrams can show a relationship between any element of a process, environment, or activity on one axis and a quality defect on the other axis. 

Get to know more about importance of project charter.

Uses of a Scatter Diagram

What is a Scatter Diagram used for? Here, we explore the three main applications of a Scatter Diagram.  

  1. It presents a relationship between two variables: However strong or weak, positive or negative, linear or non-linear; if there is a relationship to be found between two variables, a Scatter Diagram will help you find it. You can then further analyze this relationship looking at how the data points/dots are scattered across the diagram. Doing so might just lead to even more findings. 
  2. It helps you derive the value of dependent variables: As I’ve already mentioned at the start, each Scatter diagram in PMP is plotted using two variables. The value of the dependent variable (vertical axis) is influenced by the independent variable (horizontal axis). You can then study this correlation, analyze it, and come to conclusion about the probable value of the dependent variable. This is essential to analyzing several such dependent variables later. 
  3. It helps you observe patterns of data: By looking at how the data points/dots are formed on the Scatter Diagram; you can observe whether there are common or uncommon patterns. If there are several dots and they’re all closer to one another – this represents a particular kind of relationship. In the opposite scenario, where the data points are scattered all over – this shows a different relationship as well.   

Examples of Scatter Diagrams

When we talk about different types of scatter diagrams, there are mainly three of them. These variations are categorized based on how strong or weak the slope is. Another possibility exists where there isn’t any slope at all. The three types of Scatter Diagrams are: 

  • Scatter Diagram with no correlation 
  • Scatter Diagram with a moderate correlation 
  • Scatter Diagram with a strong correlation 

Scatter Diagram with No Correlation

In this Scatter diagram, the data points are spread so randomly, scattered all across the graph that you cannot plot a line through them. There is no slope/trend to be found. This means that there is no relationship or correlation between the two variables.  

Scatter Diagram with No Correlation

Image Source: Scatter Diagram (Correlation Chart): A Guide with Examples | (pmstudycircle.com)  

Scatter Diagram with a Moderate Correlation 

In this Scatter Diagram, the data points/dots are a little closer to each other. They are still scattered, which means that you cannot properly plot a straight line through them. But since they are closer to each other you can say that there is some sort of relationship between the two variables.  

Scatter Diagram with a Moderate Correlation

Image Source: Scatter Diagram (Correlation Chart): A Guide with Examples | (pmstudycircle.com)  

Scatter Diagram with a Strong Correlation

In this Scatter Diagram, as you might have correctly guessed, there is a strong correlation or relationship between the dependent and independent variable. The data points/dots are close enough that you can plot a trend line through them. In this scenario, a relationship definitely exits between the two variables.  

Scatter Diagram with a Strong Correlation

Image Source: Scatter Diagram (Correlation Chart): A Guide with Examples | (pmstudycircle.com)   

Limitations of a Scatter Diagram 

While a Scatter Diagram in PMP does help you explore possible relationships between two variables, they come with a few limitations to them as well. They are as follows: 

  1. Not more than two variables: With a Scatter Diagram, you can only explore relationships between two variables – an independent and dependent one. There’s no possibility of including a third variable and seeing how its presence impact the other two. So, even for decisions involving more than two variables, a Scatter Diagram won’t be much help. 
  2. Cannot determine the extent of a correlation: A scatter diagram cannot help you identify the full extent of the correlation between two variables. It can only tell you if a correlation is there, and how strong or weak it is.  
  3. It doesn’t measure the relationship, only change: Ideally, the objective of any analysis using Scatter diagram is to quantitatively measure the relationship between the two variables. Unfortunately, this isn’t possible. The graph only expresses the quantitative change in the value of the dependent variable. 

Scatter Diagrams for The PMP Exam

Scatter Diagram in PMP is useful in two scenarios - while preparing for the PMP exam, and while making important business decisions. Let’s explore these scenarios in further detail: 

  • Preparing for the PMP Exam: While preparing for the PMP exam, you need to know how to plot a Scatter Diagram properly and identify it. If it is a Scatter graph with a strong correlation, you need to know how to plot the trend line as well. Most importantly, you need to understand all the possible correlations between the data. 
  • Making Business Decisions: In the context of making business decisions, a Scatter Diagram can help you find a correlation between 
    • An existing process and a quality defect 
    • A business environment and a quality defect 
    • A business activity and a quality defect 

In the above three scenarios, the quality defect is the dependent variable, because it is influenced by the process, environment, or business activity in question. You and your team should be able to understand which are the actual variables in play before plotting the Scatter Diagram. 

Scattering Wisdom

While you can use scatter diagrams to determine relationships, you can also use them to verify the opposite – how distant the relationship between two variables is and use such insights to arrive at decisions. If you invest in a good pmp prep course online, you will be sure to learn the comparative advantages and disadvantages of various project management tools and techniques.  

Scatter diagrams are useful in determining the relationship between two variables. This relationship can be between two causes, or a cause and an effect. It can be positive, negative, or have no superficial correlation at all. The first variable is independent, and the second variable depends on the first. To analyze the pattern of the relationship, you change the independent variable and monitor the changes in the dependent one. A scatter diagram will help you make important business decisions while also ensuring that you’re on the right track. 

Frequently Asked Questions (FAQs)

1. What is Scatter diagram?

A scatter diagram is a visual aid commonly used in project management, but not exclusive to PMP, to find out the correlation between two variables. These variables ae plotted along the X and Y axis on a two-dimensional graph. 

2. What is the use of Scatter diagram?

Scatter diagrams are particularly useful when dealing with a large dataset that is spread over an equally large chunk of time. Scatter diagrams can help establish correlation between events and causes in such cases. Scatter diagrams can also be used to visually represent the relationship between variables in the context of other product and/or service industries. 

3. Examples of Scatter diagram in PMP exam?

As we have seen above, Scatter diagrams are of three kind; those showing a positive correlation, those showing a negative correlation, and those showing no correlation at all.

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